Automated Twist Pin Assembling Method for Interconnecting Stacked Circuit Boards in a Module

ABSTRACT

Twist pin z-axis interconnectors are assembled in columns of aligned vias in stacked printed circuit boards of a circuit module in automated assembly cycles. Each assembly cycle involves singulating a single twist pin from a plurality of twist pins, inserting the twist pin into the via column, gripping a leader portion of the twist pin, pulling the gripped leader portion until a connection portion moves into contact with the vias of the column, severing the leader portion from the connection portion, extracting the severed leader portion, and automatically repeating assembly cycles until interconnectors have been assembled into a substantial majority of the via columns of the circuit module.

CROSS REFERENCE TO RELATED APPLICATION

This invention is a division of the invention described in U.S.application Ser. No. 12/717,050, filed Mar. 3, 2010, now U.S. Pat. No.______, which is a continuation in part of the invention described inU.S. application Ser. No. 11/894,874, filed Aug. 22, 2007, now U.S. Pat.No. 7,797,821, by the inventors herein, and assigned to the assigneehereof. The subject matter of these prior applications is fullyincorporated herein by this reference.

FIELD OF THE INVENTION

This invention relates to interconnecting and assemblingthree-dimensional electronic modules from multiple stacked printedcircuit boards. More particularly, this invention relates to a new andimproved machine and method for assembling z-axis interconnectors, suchas twist pins, into columns of aligned plated through holes or viasformed in circuit boards of the module to mechanically and electricallyconnect the circuit boards and the module in an automated, efficient andrapidly executed manner. The z-axis interconnectors are preferably twistpins, which are of the type, and are used in the manner, described inU.S. Pat. Nos. 4,955,523, 5,014,419, 5,054,192, 5,045,975, 5,112,232,5,184,400, 5,189,507, 5,195,237, 6,528,759, 6,530,511, 6,584,677,6,716,038, 6,729,026 and 6,971,415, and in US patent application2009/0049684, published Feb. 26, 2009, all of which are owned by theassignee of the present invention. The subject matter of these priorpatents and patent applications is incorporated herein by thisreference.

BACKGROUND OF THE INVENTION

The evolution of computer and electronic systems has demandedever-increasing levels of performance. In most regards, the increasedperformance has been achieved by electronic components ofever-decreasing physical size. The diminished size itself has beenresponsible for some level of increased performance because of thereduced lengths of the paths through which the signals must travelbetween separate components of the systems. Reduced length signal pathsallow the electronic components to switch at higher frequencies andreduce the latency of the signal conduction through relatively longerpaths.

One technique of reducing the size of the electronic components is tocondense or diminish the space between the electronic components. Adiminished size also allows more components to be included in a system,which is another technique of achieving increased performance because ofthe increased number of components.

A particularly effective approach to condensing the size betweenelectronic components is to attach multiple semiconductor integratedcircuits or “chips” on printed circuit boards, and then stack multipleprinted circuit boards to form a three-dimensional configuration ormodule. Interconnectors are extended vertically, in the z-axisdimension, between the vertically stacked printed circuit boards, eachof which is oriented in the horizontal x-axis and y-axis dimensions. Theinterconnectors, in conjunction with conductor traces of each printedcircuit board, connect the chips of the module with short signal paths.The relatively high concentration of chips, which are connected by thethree-dimensional, relatively short length signal paths, are capable ofachieving very high levels of functionality.

The z-axis interconnectors contact and extend through plated throughholes or “vias” formed in each of the printed circuit boards. The chipsof each printed circuit board are connected to the vias by conductortraces formed on or within each printed circuit board. The vias areformed in each individual printed circuit board of the three-dimensionalmodules at similar locations, so that when the printed circuit boardsare stacked in the three-dimensional module, the vias of all of theprinted circuit boards are aligned vertically in columns along thez-axis. The z-axis interconnectors are then inserted in the column ofvertically aligned vias to establish an electrical contact andmechanical connection between the circuit boards, thus assembling themodule.

A number of different types of z-axis interconnectors have beenproposed. One particularly advantageous type of z-axis interconnector isknown as a “twist pin.” Twist pins are typically of a very small size.The most common sizes are about 0.0050, 0.0100 and 0.0150 in. indiameter. The typical length of a twist pin is about 1 to 1.5 inches.The weight of a typical four-bulge twist pin is about 0.0077 grams,making it so light that handling the twist pin is difficult. It is notunusual that a complex module formed by a 4 in. by 4 in. printed circuitboard may require the use of as many as 22,000 twist pins. Thus, therelatively large number of twist pins necessary to assemble eachthree-dimensional module makes it necessary to insert and interconnectthe circuit boards quickly and efficiently.

Assembling large numbers of twist pins or other z-axis interconnectorsin three-dimensional circuit modules has previously been accomplishedusing multiple machines to accomplish part of the assembly required. Forexample, sorting and aligning the twist pins so that they may beinserted in the column of aligned vias has been performed using one typeof machine, but the functionality of the machine still required constantoperator attention and frequent operator intervention. Another functionaccomplished by another machine involved delivering the twist pinspneumatically to the via columns. This machine required the operator toview each column of aligned vias with a microscope to determine whetherthe twist pin was properly inserted, and when an insertion error wasencountered, manually insert the twist pin. Pulling the twist pins fromthe initially inserted position was accomplished by a third type ofmachine, and a fourth machine was required to cut the leader portion ofthe twist pin. Each of these machines had to be controlled separately byspecific operator actions.

Coordinating separate machines with one another during an entire twistpin assembly cycle is tedious activity for the machine operator.Furthermore, because the operation of the different machines areindependent of one another, the functionality of one machine mayadversely influence the ability of the other machine to achieve itsdesired functionality. Even under the best of circumstances, assemblingz-axis interconnects such as twist pins into three-dimensional circuitmodules has been relatively slow and time-consuming, and thereforeinefficient and expensive. The inefficiencies and costs associated withsuch actions have created an impediment to using three-dimensionalcircuit modules with z-axis interconnects.

SUMMARY OF THE INVENTION

The present invention is directed to a single machine and a method whichis capable of assembling z-axis interconnectors in columns of alignedvias in stacked circuit boards to form three-dimensional circuitmodules, in an automated, rapid, and efficient manner. Very little or nooperator supervision or intervention is required. No human control ofmultiple assembly machines is required. The efficiency achieved fromautomatic assembly exceeds that available when multiple differentmachines must be coordinated. The three-dimensional circuit modules areassembled more quickly, are less expensive to assemble, are less likelyto experience defects, and are more reliable in construction, amongother things. Because of these benefits, the present invention makescompact three-dimensional circuit modules more desirable for use incommercial products. The present invention therefore contributessignificantly to the commercial adoption and use of three-dimensionalcircuit modules.

These and other improvements are achieved by a machine and a method forautomatically assembling z-axis interconnectors, such as twist pins,into columns of aligned vias in stacked printed circuit boards of acircuit module. Each interconnector has a leader portion and aconnection portion. The interconnectors are assembled in the via columnsin assembly cycles, and the assembly cycles are repetitiously executeduntil interconnectors have been assembled into a substantial pluralityof the via columns of the circuit module. Each assembly cycle involvesthe use of subassemblies of the machine which perform operations that:singulate one interconnector from a plurality of interconnectors, movethe circuit module and an insertion nozzle relative to one another toalign an unoccupied via column with the insertion nozzle, convey theinterconnector through a delivery tube and into the insertion nozzle,insert the interconnector into the aligned via column from the insertionnozzle, seat the interconnector in the aligned via column with theleader portion extending through the via column to a position below alower circuit board of the circuit module, grip the leader portionextending below the lower printed circuit board, pull the gripped leaderportion until the connection portion moves through the via column intocontact with the vias of the column, sever the leader portion from theconnection portion at a cutoff location adjacent to the lower circuitboard, and extract the severed leader portion.

Other desirable aspects of each each assembly cycle involve: sensing thepassage of the interconnector and the severed leader portion, sensingproper seating of the interconnector in the aligned via column, grippingand pulling the interconnector to extract it from the via column uponsensing that the interconnector is not properly seated, storing theplurality of interconnectors in a cartridge having a plurality ofreceptacles with each interconnected in a separate receptacle andaligning a pickup head with a different receptacle upon sensing that oneinterconnector was not removed from the receptacle previously alignedwith the pickup head, sensing the passage of the extracted severedleader through an extraction tube into a collection chamber, perceivingimages of an upper via of the via column by which to establish a centerposition of the upper via to insert the interconnector, using the imageof the upper via in conjunction with hole drilling map information whichspecifies locations of the vias created from holes formed duringfabrication of the printed circuit boards to align the via column andinsert the interconnector, identifying any obstruction in the via columnor any misalignment of the vias in the via column from the perceivedimage to determine whether or not to execute an assembly cycle on eachvia column, establishing the height of the upper and lower circuitboards by moving the insertion nozzle vertically to contact the uppercircuit board and by vertically moving a blade member used to grip andcut the leader portion to contact the lower circuit board, moving theinsertion nozzle vertically relative to the upper circuit board duringat least some of the assembly cycles to avoid contact with electroniccomponents connected to the upper circuit board, rotating the blademember during at least some of the assembly cycles to avoid contact withelectronic components connected to the lower circuit board, applyingintermittent force through the delivery tube and the extraction tube toattempt to respectively dislodge any stuck interconnector or severedleader, and applying intermittent force into the interconnector in thedelivery nozzle to attempt to properly seat an improperly seatedinterconnector, among other things.

A more complete appreciation of the present invention and its scope maybe obtained from the accompanying drawings, which are briefly summarizedbelow, from the following detailed descriptions of presently preferredembodiments of the invention, and from the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an automated machine for assemblingz-axis interconnects or twist pins in columns of aligned vias in stackedprinted circuit boards, in which the present invention is incorporated.

FIG. 2 is an enlarged perspective view of a twist pin pickupsubassembly, a twist pin insertion subassembly, a circuit modulepositioning subassembly, and a portion of a twist pin grip and cutsubassembly of the machine shown in FIG. 1.

FIG. 3 is an enlarged partial perspective view of the twist pininsertion subassembly, the circuit module positioning subassembly, thegrip and cut subassembly, a longitudinal movement subassembly and aleader collection subassembly of the machine shown in FIG. 1.

FIG. 4 is a side elevational view of a prior art twist pin assembledinto a circuit module by the machine shown in FIG. 1.

FIG. 5 is an enlarged cross-sectional view of the twist pin shown inFIG. 4, taken substantially in the plane of line 5-5 in FIG. 4.

FIG. 6 is an enlarged cross-sectional view of the twist pin shown inFIG. 4, taken substantially in the plane of line 6-6 in FIG. 4.

FIG. 7 is a partial vertical cross-sectional view of a prior artthree-dimensional circuit module shown in FIGS. 9A and 9B, takensubstantially in the plane of a column of aligned vias of the circuitmodule, illustrating a fully assembled twist pin of the type shown inFIG. 4 connected to the vias in the column in printed circuit boards ofthe module.

FIG. 8 is an enlarged cross-sectional view of the twist pin within a viashown in FIG. 7, taken substantially in the plane of line 8-8 in FIG. 7.

FIGS. 9A and 9B are perspective views of two different types ofthree-dimensional circuit modules formed by vertically stacked printedcircuit boards which are interconnected by twist pins in the mannershown in FIG. 7, and also illustrating electronic circuit componentsattached to upper ones of the printed circuit boards and alsoillustrating traces interconnecting some of the vias and circuitcomponents.

FIG. 9C is a partial vertical section view taken through an axis of aspacer pin used for establishing a vertically stacked or separatedrelationship of the printed circuit boards in the modules shown in FIGS.9A and 9C.

FIGS. 10A, 10B, 10C, 10D, 10E, 10F, 10G and 10H are partial, elevationaland cross-sectional views illustrating a sequence of operationsperformed in assembling the twist pin in a circuit module of the typeshown in FIGS. 7, 9A and 9B.

FIG. 11 is a perspective view of a frame of the machine shown in FIG. 1.

FIG. 12 is an enlarged perspective view of a twist pin cartridge usedwith the twist pin pickup subassembly shown in FIGS. 1 and 2, and alsoillustrating a cover plate shown in exploded relation to the twist pincartridge.

FIG. 13 is an enlarged vertical section view of a twist pin pickup headand optical sensor of the twist pin pickup subassembly shown in FIGS. 1and 2, and a partial and large vertical section view of a portion of thecartridge shown in FIG. 12, taken substantially in a plane of the pathof twist pin movement from a receptacle in the cartridge through thepickup head.

FIG. 14 is an enlarged and partial section and partial perspective viewof a twist pin insertion head and optical sensor and a camera of thetwist pin insertion subassembly shown in FIGS. 1, 2 and 3, with thesection view portion taken substantially in a plane of the path of twistpin movement in the twist pin insertion head, and also showing a partialvertical sectioned portion of a circuit module of the type shown inFIGS. 9A and 9B with a twist pin delivered and seated in a column ofvertically aligned vias.

FIG. 15 is an enlarged vertical section view of the twist pin insertionsubassembly shown in FIGS. 1-3 and a transfer support beam shown inFIGS. 1-3, in which a portion of a linear motor of the twist pininsertion subassembly is broken away to reveal certain internalcomponents.

FIG. 16 is an enlarged and exploded view of the longitudinal movementsubassembly and a more enlarged perspective view of the grip and cutsubassembly shown in FIGS. 2 and 3, in which a portion of alinear/rotational motor of the longitudinal movement subassembly isbroken away to reveal certain internal components.

FIG. 17 is a side elevational view of the components shown in FIG. 16,which are assembled and attached to a granite slab and positioned withrespect to a circuit module retained by the circuit module positioningsubassembly of the machine shown in FIGS. 1, 2 and 3.

FIG. 18 is an exploded perspective view of the grip and cut subassemblyshown in FIGS. 16-17.

FIG. 19 is an enlarged vertical section view of the grip and cutsubassembly shown in FIGS. 16-18.

FIG. 20 is a further enlarged vertical section view of a blade activatorportion of the grip and cut subassembly shown in FIG. 19, in which theplane of the view is rotated 90° with respect to the plane of view ofFIG. 19.

FIGS. 21, 22 and 23 are enlarged vertical section views of an upperportion of a pinch and cut blade and a blade deflecting mechanism of thegrip and cut subassembly shown in FIGS. 16-20, taken in a planesubstantially parallel to the movement of the pinch and cut blade andshowing the pinch and cut blade positioned in an open position, apartially closed position and a fully closed position, respectively.

FIG. 24 is an enlarged, vertical section view of an venturi device andan optical sensor of the leader collection subassembly shown in FIGS. 1,3, 16 and 17.

FIGS. 25A and 25B together constitute a block and schematic diagram of acontrol system of the machine shown in FIG. 1.

FIGS. 26A, 26B and 26C form a single flow chart of the programmedsequence of operations created by the control system shown in FIGS. 25Aand 25B to cause the machine shown in FIG. 1 to operate as describedherein.

DETAILED DESCRIPTION Machine and Method in General

A fully automated machine 30 which embodies the present invention isshown in FIG. 1. The machine 30 assembles twist pins 34 (FIG. 4), orother z-axis interconnectors, into columns 58 of vertically alignedplated through holes or vias 60 (FIGS. 7, 10A-10H) in vertically spacedor stacked printed circuit boards 32 (FIG. 7) to form three-dimensionalcircuit modules 36 (FIGS. 9A and 9B). The twist pins 34 establishthree-dimensional electrical connections between conductors or traces 38and electronic circuit components 40 on the printed circuit boards 32 ofeach module 36 (FIGS. 9A and 9B).

As shown in more detail in FIGS. 1, 2 and 3, the machine 30 includes aframe 42 (FIG. 11) which supports various subassemblies of the machine30. A twist pin pickup subassembly 44 uses a twist pin pickup head 46(FIG. 13) to pneumatically remove a twist pin 34 (FIG. 4) from acartridge 50 (FIG. 12) and to pneumatically convey the removed twist pinthrough a delivery tube 52 to a twist pin insertion subassembly 54. Thetwist pin insertion subassembly 54 uses an insertion head 56 with aninsertion nozzle 57 (FIG. 14) to deliver the twist pin 34 into a column58 of vertically aligned plated through holes or vias 60 of thevertically stacked printed circuit boards 32 (FIG. 10A). Upon insertion,a leader portion 64 of the twist pin 34 extends completely through thecolumn 58 of vias 60 and a leading end of 78 of the leader portion 64extends below the lower printed circuit board of the module (FIG. 10B).

A circuit module positioning subassembly 68 of the machine 30 includesan XY positioning table 70. The XY positioning table 70 locates thecolumns 58 of the aligned vias 60 in the printed circuit boards 32 inalignment with the twist pin insertion nozzle 57 to receive the twistpin 34 (FIGS. 10B and 14) when inserted. A linear motor 72 (FIG. 15) ofthe twist pin insertion subassembly 54 moves the insertion head 56vertically upward and downward to achieve a desired spacing of theinsertion nozzle 57 from a via 60 in the uppermost printed circuit board32 in the module 36.

When the twist pin 34 is inserted in the vertical column 58 of alignedvias 60, a grip and cut subassembly 74 of the machine 30 moves a pinchand cut blade 76 to pinch and grip a leading end 78 of the leaderportion 64, after the leader portion 64 is inserted through the column58 of aligned vias 60. The leading end 78 of the leader 64 extendsbeneath and beyond the lower circuit board 32 of the module 36 (FIGS.10B, 10C and 14). A longitudinal movement subassembly 80 verticallymoves the grip and cut subassembly 74 and its connected pinch and cutblade 76 in a linear path which is coincident with the column 58 ofaligned vias and the path through which the insertion head 56 deliversthe twist pin 34. A linear/rotational motor 82 of the longitudinalmovement subassembly 80 pulls the grip and cut subassembly 74 downward,and the gripped twist pin 34 moves downward through the column 58 ofaligned vias 60. The downward movement continues until bulges 84 of thetwist pin 34 are located in and are radially compressed againstsidewalls 86 of each via 60 (FIGS. 10E and 10F). Thereafter, the gripand cut subassembly 74 moves the pinch and cut blade 76 to release itsgrip on the leading end 78 of the leader 64, and the linear/rotationalmotor 82 returns the grip and cut subassembly 74 and the pinch and cutblade 76 to a position adjacent to the lower printed circuit board 32(FIG. 10F). The grip and cut subassembly 74 then moves the pinch and cutblade 76 to cut or sever the leader 64 of the twist pin 34 at a cutoffend 88, leaving the remaining portion of the twist pin 34 with itsbulges 84 in contact with the sidewalls 86 of the vias 60 (FIGS. 7 and10H). The cutoff end 88 of the twist pin 34 is located slightly beyondthe lower printed circuit board 32.

A leader collection subassembly 90 (FIG. 3) uses a venturi device 92(FIG. 24) to pneumatically extract the severed leader 64 from the gripand cut subassembly 74 and the longitudinal movement subassembly 80. Theextracted severed leader 64 is deposited into a collection chamber 96 ofthe machine 30. Extracting and collecting the severed leaders 64prevents them from interfering with the operation of the machine 30.

After one twist pin 34 has been extracted from the cartridge 50 by thepickup subassembly 44, the cartridge 50 is moved to a new position by anXY positioning device 98, to provide another twist pin for the nextsubsequent interconnect assembly cycle. Similarly, the XY positioningtable 70 of the circuit module positioning subassembly 68 moves thecircuit module 36 to locate another column 58 of aligned vias 60 beneaththe insertion nozzle 57 of the insertion head 56 of the insertionsubassembly 54. The linear motor 72 of the insertion subassembly 54moves the insertion head 56 vertically to clear the insertion nozzle 57from contact with any electronic circuit component 40 that might beattached to the upper circuit board 32 (FIGS. 9A and 9B). Once anothertwist pin 34 is available from the pickup subassembly 44, and anothercolumn 58 of aligned vias 60 is oriented to receive that twist pin bythe circuit module positioning subassembly 68, the next twist pin isautomatically inserted in the column 58 of aligned vias 60, the leader64 of the inserted twist pin 34 is pulled to move the twist pin 34downward until the bulges 84 are located within the vias 60 and thebulges 84 compress against the sidewalls 86 of the vias 60, the leader64 is cut off at the cutoff end 88, and the severed leader 64 isextracted and transported to the collection chamber 96.

The twist pin 34 is removed from the cartridge 50 pneumatically by lowpressure air or gas and is conveyed through the delivery tube 52pneumatically by high pressure gas. The grip and cut subassembly 74operates pneumatically by low and high pressure gas to grip and cut theleader 64 with the pinch and cut blade 76. The severed leader 64 isextracted pneumatically by low pressure gas and is conveyed into thecollection chamber 96.

Electric linear motors 100 and 101 (FIGS. 3 and 25A) operate the XYpositioning table 70 of the circuit module positioning subassembly 68.The linear/rotational motor 82 of the longitudinal movement subassembly80 and the linear motor 72 of the twist pin insertion subassembly 54 arealso electric motors. Linear motors are precisely controllable toachieve highly precise positioning of the XY positioning table 70 veryquickly. Electric stepper motors 102 and 104 preferably operate the XYpositioning device 98 of the pickup subassembly 44. An electric servomotor 106 (FIG. 16) is used as part of the linear/rotational motor 82 ofthe longitudinal movement subassembly 80 to rotate the grip and cutsubassembly 74 as necessary to avoid contact with electronic circuitcomponents 40 which may be located on the lower printed circuit board 32of the circuit module 36 (FIG. 17).

An optical sensor 108 (FIG. 13) is employed in the pickup head 46 of thepickup subassembly 44 to verify that the twist pin 34 has been properlyremoved from the cartridge 50 and conveyed into the delivery tube 52.Another optical sensor 110 (FIG. 14) is used in the insertion head 56 ofthe insertion subassembly 54 to verify that the twist pin 34 has beendelivered from the delivery tube 52 and is properly seated in the column58 of aligned vias 60 (FIG. 10B). An optical sensor 112 (FIG. 24) isused in the venturi device 92 of the leader collection subassembly 90 toverify that the severed leader portion 64 has been extracted from thegrip and cut subassembly 74 and from the longitudinal movementsubassembly 80.

An optical camera 116 (FIGS. 14 and 15) is employed as part of theinsertion subassembly 54 to verify and establish the precise location ofthe vertical columns 58 of aligned vias 60, thereby improving theaccuracy of inserting the twist pin 34. The optical camera 116 is alsoused to determine whether the vias 60 are aligned sufficientlyvertically in the column 58 to permit the successful insertion of atwist pin. The optical camera 116 is also used to detect any significantobstruction that might be located in any one of the via columns 58 andwhich might prevent the successful insertion of a twist pin 34 in thatvia column.

A light curtain 117 (partially shown in FIG. 1) extends around areas ofthe machine 30 where work is performed. The light curtain 117 is formedby linear light beam receiving arrays 118 a, 118 b and 118 c whichreceive receives individually focused and narrow beams of light createdby correspondingly-positioned linear light beam emitting arrays 119 a,119 b and 119 c. The linear light beam emitting and receiving arrays arelocated around the front and left and right sides of the machine 30where a machine operator will normally stand and interact with themachine. Should any one of the individual beams be broken by theinsertion of an operator's hand or some foreign object, for example, themachine 30 will immediately stop functioning. The light curtain is asafety feature of the machine 30 which is intended to prevent injury tothe machine operator or to prevent the continued operation of themachine 30 if some foreign object unexpectedly enters the twist pinassembly area.

A control system 120, shown in FIGS. 25A and 25B, controls the sequenceof automatic operations performed by the machine 30. The control system120 supplies electrical control signals to the electric motors 72, 82,100, 101, 102, 104 and 106 to establish the positions of the devicesconnected to those electric motors; supplies electrical signals tocontrol the application gas pressure to operate the grip and cutsubassembly 74 and to perform the twist pin and severed leader removal,extraction and transportation functions; responds to signals from theoptical sensors to determine the proper movement of each twist pin 34and the severed leader 64; receives information from the optical camera116 to verify and establish the location of the columns 58 of alignedvias 60, to determine whether the vias 60 in the column are alignedsufficiently, and to determine whether obstructions exist in the columns58 of vias 60; and controls the operation of the machine 30 in relationto whether or not any of the light beams of the light curtain 117 arebroken. The control system 120 establishes and controls the sequence ofthe automated operations performed by the machine 30, as shown in FIGS.26A, 26B and 26C.

More details concerning the twist pins 34, the three dimensional circuitmodule 36, the pickup subassembly 44, the twist pin insertionsubassembly 54, the circuit module positioning subassembly 68, the gripand cut subassembly 74, the longitudinal movement subassembly 80 and theleader collection subassembly 90, as well as of the pneumatic,electrical and optical aspects of the control system 120 and itssequence of operations are discussed below.

Twist Pins

The twist pins 34 are conventional and an example of one is shown inFIG. 4. The twist pin 34 is fabricated from strands of gold-plated,beryllium-copper wire which have been formed conventionally by helicallycoiling a number of outer strands 126 around a center core strand 128 ina planetary manner, as shown in FIG. 5. At selected positions along thelength of the wire 124, one bulge 84 is formed by untwisting the outerstrands 126 in a reverse or anti-helical direction. As a result ofuntwisting the strands 126 in the anti-helical direction, the spaceconsumed by the outer strands 126 increases, causing the outer strands126 to bend or expand outward from the core strand 128 and create alarger diameter for the bulge 84 than the diameter of the regularstranded wire 124. The laterally outward extent of the bulge 84 isillustrated in FIG. 6, compared to FIG. 5. The strands 126 and 128 ofthe wire 124 have the necessary mechanical characteristics to maintainthe shape of the wire in the stranded configuration and to allow theouter strands 126 to bend outward at each bulge 84 when untwisted.

The bulges 84 are formed at selected predetermined distances along thelength of the wire 124 to contact the sidewalls 86 of the vias 60 inprinted circuit boards 32 of the circuit module 36, as shown in FIG. 7.One bulge 84 contacts the sidewall 86 of each via 60 when the twist pin34 is pulled through the vertical column 58 of aligned vias 60. Theouter strands 126 of the bulge 84 have sufficient resiliencecharacteristics to press against an inner surface of the sidewall 86,thereby establishing an electrical and mechanical connection between thetwist pin 34 and the via 60, as shown in FIG. 8.

The strands 126 and 128 at the leading end 78 of the leader 64 have beenwelded or fused together to form a rounded or parabolic configuration tofacilitate insertion of the leader 64 through the column 58 of vias 60.The leader 64 has sufficient length to extend through the entire column58 when the bulge 84 which adjoins the leader 64 makes contact with theupper via 60 of the upper printed circuit board 32 in the column 58.Under these conditions, the leading end 78 of the leader 64 extendsbelow the lower via of the lower printed circuit board 32.

The leading end 78 of the leader 64 is gripped from below and is pulleddownwardly, causing the bulges 84 to move downwardly through thevertically aligned vias 60 until the bulges 84 are all aligned and incontact with the sidewalls 86 of the vias 60 of the stacked printedcircuit boards 32. To position the bulges 84 in contact with the vias60, all but the uppermost bulge 84 of the twist pin 34 is pulled intoand out of at least one via 60 in the column 58 until the twist pin 34arrives at its final position. The resiliency of the bulges 84 allowsthem to move in and out of the vias 60 without losing their ability tomake firm contact with the sidewalls 86 of the vias 60 in the finalassembled position. Once the twist pin 34 is in the final assembledposition, the leader 64 is cut off at the cutoff end 88. The cutoff end88 may be located flush with the lower circuit board 32, or moretypically is located to extend no greater than 0.015 inch beyond thelower circuit board 32.

At the other end of the twist pin 34, the strands 126 and 128 are fusedor welded together at a tail end 129 of the twist pin. In the assembledposition, the tail end 129 can extend a short distance above the uppersurface of the upper printed circuit board 32, but more typically thetail end 129 is located at a flush or sub-flush position relative to theupper surface of the upper circuit board 32. Allowing the cut-off end 88to extend slightly below the lower printed circuit board of the module36 facilitates gripping the twist pin 34 at the cutoff end 88 if itbecomes necessary to remove the twist pins to disassemble the module 36to repair or replace any defective components.

Twist pins 34 are typically of a very small size and weight. The mostcommon diameters of the coiled strands 126 and 128 in the twist pin 34are about 0.0016, 0.0033 and 0.0050 in. The diameters of the coiledstrands of the wire 124 formed from the these sizes of strands 126 and128 are 0.005, 0.0100, and 0.0015 in., respectively. The typical lengthof a twist pin 34 having four to six bulges is about 1 to 1.5 inches,with the leader 64 constituting about half of this length. The outerdiameter of each bulge 84 is approximately two times the diameter of thestranded wire 124. The typical weight of a four-bulge twist pin is about0.0077 grams.

Circuit Module

The circuit module 36 shown in FIG. 9A is formed by four printed circuitboards 32. A similar circuit module 36 could be formed by more or lessprinted circuit boards 32. The circuit boards 32 are physically andmechanically separated from one another by spacer pins 130 which arepreferably located in holes formed at each corner of the circuit boards32. The details of one spacer pin 130 is shown in FIG. 9C.

Each spacer pin 130 includes multiple coaxially oriented segments 131,132 133, and 134 of increasing diameter extending from top to bottom (asshown) along the length of the pin 130. A segment 135 having a smallerdiameter than the larger diameter segment 134 above it is also in acoaxial relationship with the other segments of the pin 130. Transitionsbetween the segments 131, 132 and 132, 133 and 133, 134 and 134, 135create shoulders which contact the upper and lower surfaces ofinsulating substrates 138 of the printed circuit boards 32. The holesformed in the insulating substrates 138 receive the segments 131, 132,133 and 135. With the spacer pin 130 inserted into the holes in theinsulating substrates, the shoulders between the transitions define thespaced apart relationship of the printed circuit boards as establishedby the distance between the shoulders. The holes formed in theinsulating substrates have a slightly smaller diameter than thediameters of the segments which fit within those holes. The printedcircuit boards must be firmly pushed into the segments, thereby creatingsignificant frictional retention between the segments of the pin 130 andthe insulating substrates 138. The frictional retention holds theprinted circuit boards 32 firmly in position to allow the twist pins tobe inserted in the via columns.

Once the twist pins are inserted in all of the via columns of thecircuit module 32, a substantially greater additional retention forcebetween the circuit boards 32 results from the additional retention andrigidity created by assembling the twist pins in the via columns. Thecompression of the bulges 84 against the sidewalls 86 (FIG. 7)establishes additional restraint on the circuit boards, to resistvertical separation and lateral skewing. The spacer pins 130 and thetwist pins 34 thereby mechanically retain the circuit boards in thevertically separated or vertically spaced relationship. Although notshown, interior spacer pins 130 could also be employed to physically andmechanically separate and connect the circuit boards 32 at selectedinterior locations spaced inward from the edges of the circuit boards.

Each of the circuit boards 32 uses an electrically insulating substrate138 (FIG. 7), through which holes have been drilled. Metallic conductivematerial, such as copper, is deposited into the drilled holes and overthe upper and lower surfaces of the insulating substrate 138 usingconventional printed circuit board plating techniques. The deposition ofthe conductive material on the inside cylindrical surfaces of the holesresults in the formation of the metallic sidewalls 86 (FIG. 8) of thevias 60. The layer of deposited conductive material on the upper andlower planar surfaces of the insulating substrate 138 is thereafteretched away in selected patterns using conventional printed circuitboard lithographic etching techniques. An annular ring 139 (FIG. 7)surrounding and integrally connected to the sidewalls 86 on oppositesurfaces of the insulating substrate 138 is left in place (not etchedaway) to complete each via 60. Connective portions of the layer ofdeposited conductive material are also retained (not etched away) on theupper and lower planar surfaces of the insulating substrate 138, andthese connective portions of conductive material form the traces 38. Thetraces 38 connect selected annular rings 139 of the vias 60, and therebyestablish an electrical connection between the selected vias 60. It isthrough the vias 60 and the traces 38 that electrical signals,electrical power and electrical ground reference potential aredistributed throughout each printed circuit board 32.

All of the printed circuit boards 32 which form the circuit module 36need not be of the same size, as is illustrated by the circuit moduleshown in FIG. 9B. In this circuit module 36, the upper printed circuitboard 32 is smaller in size than the other three printed circuit boards.Spacer pins 130 extend between the corners of the upper circuit board 32located in the middle of the circuit module and between the othercircuit boards. All of the circuit boards 32, even though of differentsizes, are connected together firmly in the module using the spacer pins130. Bolts and nuts and spacing devices (none shown) may be used asalternatives to the spacer pins 130.

The twist pins 34 which extend through the vias 60 of the four-boardportion of the circuit module on the left as shown in FIG. 9B requirethe use of four bulges 84. The twist pins 34 which extend through thevias 60 of the three-board portion of the circuit module on the right asshown in FIG. 9B require the use of three bulges 84. Under circumstanceswhere twist pins 34 of different lengths will be inserted in columns 58of vias 60 at different locations in the circuit module 36, due todifferent numbers of printed circuit boards used in assembling thecircuit modules 36, as exemplified by FIG. 9B, multiple lengths of twistpins 34 will be contained in the cartridge 50, and the proper lengthtwist pin will be selected by the twist pin pickup subassembly 44according to the location of the column 58 of vias 60 into which thepins will be inserted. The height of the insertion nozzle 57 above theupper circuit board 32 of the module 36 will also be adjusted by themotor 72 of the insertion subassembly 54 (FIG. 15), to insert differentlength twist pins in via columns of circuit modules having differentheight upper circuit boards.

Although each printed circuit board 32 is shown in FIGS. 9A and 9B ashaving deposited conductive material only on the upper and lowersurfaces of the insulating substrate 138, multilayer printed circuitboards may also be used in the present invention. Multilayer printedcircuit boards are formed by laminating together a plurality oftwo-sided circuit boards, using a layer of insulating adhesive betweeneach two-sided circuit board. The resulting multilayer printed circuitboard includes interior traces embedded within the center of themultilayer printed circuit boards, in addition to those traces 38located on the exterior surfaces of the multilayer circuit boards.

Electrical circuit components 40, such as integrated circuits anddiscrete electrical components, are typically attached to at least someof the printed circuit boards 32 of the circuit module 36. Thecomponents 40 may be connected directly to the vias 60 or traces 38. Thecomponents may also be connected by sockets or other conventionalinterconnect interface devices that are connected to the vias 60 ortraces 38, and then the components 40 are connected to those interfacedevices in a conventional manner. Electrical components 40 are shownattached to the upper printed circuit boards 32 in FIGS. 9A and 9B, andto both the upper and lower printed circuit boards 32 in FIG. 17.Circuit components 40 could also be connected to the middle printedcircuit boards between the upper and lower circuit boards of the circuitmodule 36, provided that those circuit components have a sufficientlyshort height to fit within the space between adjacent circuit boards 32in the module 36.

The arrangement of the vias 60 in each circuit board 32 and theinterconnection of those vias with the traces 38 establishes the signalpaths for the electrical signals conducted by each circuit board 32. Thetwist pins 34 establish the electrical signal paths for the electricalsignals conducted between the circuit boards 32 in the module 36. Thetwist pins 34 are fully conductive along their entire length, allowingthe signals to be distributed from the vias 60 to the traces 38 of eachcircuit board 32 of the module 36. In those cases where it is notdesired to distribute a signal conducted by a twist pin to a via 60 ofone circuit board 32, the via 60 through which the twist pin extends isnot connected by a trace 38 to any other component on that printedcircuit board.

A relatively large number of three-dimensional signal paths can becreated in each circuit module 36, due to the very small spacing betweenvias 60 and a relatively large number of narrow traces 38 of eachprinted circuit board 32. The spacing shown in FIGS. 9A and 9B isexaggerated for purposes of illustration. In actuality, a very highdensity of traces 38 and vias 60 can be formed in a small amount ofspace. Such high density three-dimensional signal paths shorten theconductive paths and allow the circuit components 40 to function athigher switching rates and with more dense signal conductivity, amongother things, thereby improving performance.

The large number of three-dimensional signal paths can become verycomplex. A complete and accurate understanding of the layout of the vias60 and traces 38 in the circuit boards 32 of the circuit module 36 isrequired to establish the desired signal paths. Typically, the vias 60and the traces 38 are laid out using computer controlled circuit designand layout software programs to create precise placement and connectionof the signal paths on each printed circuit board 32. Such computercircuit design and layout programs establish the physical location anddimension of the traces 38, and the connection of the traces with thevias 60 in each of the circuit boards 32 of the module 36.

To ensure precision in the location of the holes drilled into theinsulating substrate 138 (FIG. 7) before the conductive material isdeposited on the substrate 138, computer controlled hole drilling mapsare derived from the computer circuit design and layout programs used infabricating the printed circuit boards. The hole drilling map specifiesthe location where each of the holes is drilled in the substrate 138that becomes a via 60 once the conductive metal is deposited in thehole.

Computer numerically controlled drilling machines drill the holes in thesubstrate 138 in the locations specified by the drilling map. Eachcircuit board 32 includes registration markings called “fiducials” whichare used by the drilling map software to orient the layout of theprinted circuit board and thereby define the positions where the holesare drilled in the insulating substrate 138.

Fiducials 144 are formed on the upper circuit board of the circuitmodules, as shown in FIGS. 9A and 9B. The fiducials 144 are exemplifiedby marks or plated registration points formed on each of the circuitboards 32. The fiducials 144 are optically identified by the camera 116(FIGS. 14 and 15) before any twist pins are assembled into each circuitmodule 36. The control system 120 (FIGS. 25A and 25B) uses theinformation from the hole drilling map, the optical registrationinformation obtained from the camera 116, and other information obtainedfrom the camera 116 to move the XY positioning table 70 of the circuitmodule positioning subassembly 68 and thereby locate each column 58 ofvias 60 coincident with an axis 145 through the insertion nozzle 57(FIG. 14) along which the twist pins are delivered. Such automatedpositioning ensures that each column 58 of the aligned vias 60 is in thebest position to receive the leader 64 of the twist pin 34 when it isinserted (FIGS. 10A and 10B).

To move each column 58 of vias 60 so that its center location iscoincident with the axis 145 through an insertion nozzle 57 of theinsertion head 56 (FIG. 14), each circuit module 36 must be held in afixed position on the XY positioning table 70 of the circuit modulepositioning subassembly 68. Each circuit module 36 is immovably attachedto a pallet 146, shown in FIGS. 1-3 and 17, and the pallet 146 isimmovably connected to the XY positioning table 70 by conventionalregistration devices (not shown) which interact between the positioningtable 70 and the pallet 146. The pallet 146 includes at least one openreceptacle 148 (FIG. 17) into which one three-dimensional circuit module36 is received and locked in place by use of a conventional retentiondevice (not shown) associated with each receptacle 148. The circuitmodule 36 is placed within the open receptacle 148 and immovablyconnected to the pallet 146 before any twist pins are inserted in thevias of that circuit module 36. The immovable connection of the circuitmodule 36 to the pallet 146 and the immovable connection of the pallet146 to the XY positioning table 70 assure that the XY positioning table70 can precisely align the columns 58 of vias 60 with the axis 145through the insertion nozzle 57 of the insertion head 56 (FIG. 14).

As shown in FIG. 1, a plurality of circuit modules 36 can be connectedto the pallet 146 in a corresponding number of receptacles 148. Thetwist pins 34 are assembled into all the circuit modules without theneed to assemble the twist pins into one circuit module and then unloadit from the XY positioning table before another module is assembled withtwist pins. The fiducials 144 of each circuit module 36 are opticallyidentified by the camera 116. The location information of the fiducials144 is correlated to the hole drilling map information, and the locationof each column 58 of vias in each circuit module 36 is then establishedfrom the hole drilling map information. In addition, the optical camera116 is then used to evaluate the upper via 60 of each column 58 todetermine whether it is centered in the location specified by the holedrilling map information. Optical recognition software used by thecontrol system 120 (FIGS. 25A and 25B) responds to an optical pattern oflight projecting upwardly through the column 58 of vias 60 to preciselyidentify the center of each via column 58. Adjustment information isapplied to the hole drilling map information to precisely locate thecenter of each column 58. By using the precise center of each column 58of the vias 60, the control system 120 moves the XY positioning table 70to locate the center or axis of column 58 with the axis 145 through theinsertion nozzle 57 (FIG. 14). The precise positions of the holelocations greatly facilitates the successful insertion of a twist pin inthe column 58 (FIG. 10B). One twist pin is assembled in each column 58of vias 60 in one interconnect assembly cycle, until twist pins 34occupy all of the columns 58 of vias in the circuit module 36.

Assembly Cycle

Each interconnect or twist pin assembly cycle is automatically executedby the machine 30. Each assembly cycle includes inserting the twist pin34 in the column 58 of aligned vias 60, pulling the twist pin to thelocation where the bulges 84 are compressed against the sidewalls 86 ofthe vias 60, severing the leader portion 64 while leaving the portion ofthe twist pin 34 with the bulges 84 in contact with the vias, andextracting the severed leader 64. The movement of a twist pin 34 duringan assembly cycle is illustrated in FIGS. 10A-10H.

The twist pin 34 is delivered to the column 58 of aligned vias in aleader-first manner, as shown in FIG. 10A. The rounded leading end 78 ofthe twist pin 34, which may advantageously assume a parabolic shape,facilitates entry into the column 58. Once properly inserted, the leader64 is of sufficient length to position the leading end 78 below andbeyond the lower circuit board 32, as shown in FIG. 10B. Locating theleading end 78 of the leader 64 beyond the lower circuit board 32permits it to be gripped by the pinch and cut blade 76, as shown in FIG.10C.

The pinch and cut blade 76 includes two flexible jaw members 150 and 152which move toward and away from one another as a result of movementimparted to the pinch and cut blade 76 by the grip and cut subassembly74 (FIGS. 21-23). The terminal ends of the jaw members 150 and 152 areformed as sharp cutting wedges 154 and 156, respectively. The cuttingwedges 154 and 156 face one another across an open space between the jawmembers 150 and 152. As shown in FIG. 10C, the jaw members 150 and 152move together sufficiently in a partially closed position to pinch thecutting wedges 154 and 156 into the sides of the leader 64 at itsleading end 78. The cutting wedges 154 and 156 pinch into the sides ofthe leader 64 to the extent necessary to firmly grip the leader 64without severing it, so that the twist pin 34 can be pulled. The cuttingwedges 154 and 156 are positioned adjacent to the lower circuit board 32by the movement of the linear/rotational motor 82 of the longitudinalmovement subassembly 80, before the jaw members 150 and 152 are movedtoward one another to pinch the cutting wedges 154 and 156 into thesides of the leader 64.

Next, as shown in FIG. 10D, the pinch and cut blade 76 is moved downwardrelative to the circuit boards 32 of the module 64 by the longitudinalmovement subassembly 80, while the grip and cut subassembly 74 biasesthe jaw members 150 and 152 to maintain the cutting wedges 154 and 156pinched into the sides of the leader 64. The linear/rotational motor 82of the longitudinal movement subassembly 80 pulls the twist pin 34downward the correct distance to position the bulges 84 in contact withthe sidewalls 86 of the vias 60 in the column 58. The lower bulges 84(as shown) move into and out of the upper vias 60 until the twist pinachieves its final assembled position.

As shown in FIG. 10E, the pinch and cut blade 76 pulls the twist pin 34downward to its predetermined final position where the bulges 84 arelocated in contact with the sidewalls 86 of the vias 60 of the viacolumn 58. The extent of downward movement represented in FIG. 10E isestablished by the amount of longitudinal movement of the longitudinalmovement subassembly 80. With the twist pin 34 pulled into place, thejaw members 150 and 152 move apart to an open position to release theleader 64. The bulges 84 remain resiliently compressed against thesidewalls 86 of the vias 60 to hold the twist pin 34 in place in theassembled position.

Next, as shown in FIG. 10F, the pinch and cut blade 76 is moved to anupper cutting position, at which the cutting wedges 154 and 156 areslightly spaced below the lower circuit board 32. The linear/rotationalmotor 82 of the longitudinal movement subassembly 80 moves the grip andcut subassembly 74 and the pinch and cut blade 76 upward to this desiredposition. To permit the movement represented in FIG. 10F, the jawmembers 150 and 152 move to an open position and separate transverselyaway from the position shown in FIG. 10E, thereby spacing the cuttingwedges 154 and 156 laterally away from the outside surface of the leader64. In this open position, the jaw members 150 and 152 and the cuttingwedges 154 and 156 do not interfere with the upward movement of thepinch and cut blade 76 from the position shown in FIG. 10E to theposition shown in FIG. 10F. The open position of the jaw members 150 and152 allows the leader 64 to pass between the cutting wedges 154 and 156.

The longitudinal movement subassembly 80 moves the pinch and cut blade76 along an axis which is vertically coincident with the axis 145 of theinsertion nozzle 57 where the leader 64 is located. The leader 64 entersa conduction tube 162 of the grip and cut subassembly 74. The conductiontube 162 is positioned concentrically about the central axis 145.

The leader 64 is next severed by lateral inward movement of the jawmembers 150 and 152 to the fully closed position, as shown in FIG. 10G.The cutting wedges 154 and 156 move together and sever the leader 64from the bulged portion of the twist pin 34 which remains in the finalassembled position within the module 64. The leader 64 is severed fromthe twist pin 34 at the cut-off end 88. Movement of the grip and cutsubassembly 84 causes the jaw members 150 and 152 to move toward oneanother and force the cutting wedges 154 and 156 completely through theleader 64, thereby severing the leader.

Finally, as shown in FIG. 10H, the severed leader 64 is extracted andtransported away by the application of low air pressure or vacuum withinthe conduction tube 162 created by the venturi device 92 (FIGS. 3 and24). The conduction tube 162 transports the severed leader 64 from thegrip and cut subassembly 74 to prevent the severed leader 64 frominterfering with the operations of the machine 30 in the next subsequentinterconnect assembly cycle. The severed portion of the leader istransported away from the grip and cut subassembly 74 and thelongitudinal movement subassembly 80 through the conduction tube 162 andis delivered to and collected in the collection chamber 96 (FIGS. 3 and24) of the leader collection subassembly 90. Simultaneously withremoving the severed leader 64, the jaw members 150 and 152 are movedaway from one another to the open position to be ready to execute thenext subsequent assembly cycle.

The subassemblies of the machine 30 automatically execute the followingoperations of assembling the twist pin in a via column (FIGS. 10A-10H):removing and singulating the twist pin, delivering the singulated twistpin to the column of vias, inserting the twist pin in the column ofvias, gripping the twist pin, pulling the twist pin into the finalposition, severing the leader from the bulged portion of the twist pinremaining in the column 58, extracting the severed twist pin, and movingthe circuit module 36 to align another column of vias for insertion ofthe twist pin. The automatic execution of these operations iscoordinated among the subassemblies, and the overall assembly cycle isperformed in a rapid continuous sequence which is continuously repeated.Operating in this manner, the machine 30 is capable of automaticallyassembling many twist pins in many via columns to complete circuitmodules very quickly, efficiently and cost-effectively.

More details of the mechanical nature and specific operational aspectsof the various components and subassemblies of the machine 30 aredescribed below.

Frame and Component Support

The subassemblies of the machine 30 are all connected to and supportedby the frame 42 shown in FIG. 11 (also FIG. 1). The frame 42 ispreferably formed by pieces of rectangular rigid steel tubing which havebeen welded or otherwise fastened together in the configuration shown.The frame 42 includes a lower, three-dimensionally-shaped rectangularbase support structure 172. The base support structure 172 supports aslab of granite 174 (FIGS. 1-3 and 17), creating a table-likeconfiguration to which the circuit module positioning subassembly 68,the grip and cut subassembly 74, the longitudinal movement subassembly80 and portions of the leader collection subassembly 90 are allconnected. The granite slab 174 is of substantial weight and inertia,and the inertia of the granite slab 174 substantially diminishes anddampens the reactive effects of the moving components of thesubassemblies, thereby eliminating mechanical disturbances which wouldadversely affect the alignment and positioning necessary to achievereliable twist pin insertion.

The base support structure 172 has an intermediate level rectangularconfiguration 176 formed by a front intermediate transverse piece 178 a,a rear intermediate transverse piece 180 a, and left and rightintermediate longitudinal pieces 182 a and 184 a. A similarly shapedlower level rectangular configuration 186 is formed by similarly-shapedfront lower transverse piece 178 b, a rear lower transverse piece 180 b,and left and right lower longitudinal pieces 182 b and 184 b. The pieces178 b, 180 b, 182 b and 184 b are located directly below and orientedsimilarly to the corresponding pieces 178 a, 180 a, 182 a and 184 awhich form the intermediate level configuration 176. The intermediateand lower level configurations 176 and 186 are separated by verticalseparation pieces 188. The intermediate and lower level configurations176 and 186, along with the vertical separation pieces 188, form thebase support structure 172.

Two center support beams 190 a and 192 a are located within theintermediate-level configuration 176. The upper center beams 190 a and192 a extend parallel to the longitudinal pieces 182 a and 184 a, andare connected to the vertical separation pieces 188 which extend betweenthe intermediate and lower configurations 176 and 186. The lowerconfiguration 186 also includes similarly shaped lower center beams 190b and 192 b which are located directly below and oriented similarly tothe corresponding center support pieces 190 a and 192 a.

The center support beams 190 a and 192 a support the granite slab 174. Alayer of elastomeric material (not shown) is placed on top of the pieces190 a and 192 a before the granite slab 174 is attached to the centerbeams 190 a and 192 a. The layer of elastomeric material further dampensand isolates the inertia of the granite slab 174 from externalenvironmental influences transferred to the frame 42.

Plates 194 extend across the corners of the lower level rectangularconfiguration 176, at the inside of the intersections of the pieces 178b, 182 b and 178 b, 184 b and 180 b, 182 b and 180 b, 184 b.Conventional casters 196 (FIG. 1) are connected to the plates 194 toallow the machine 30 to be rolled to a desired use position. Thereafter,conventional vibration isolators 198 (FIG. 1) are extended downward tosupport the machine 30 from a floor or other support surface andeliminate weight on the casters 196. The vibration isolators 198(FIG. 1) are connected at the corners of the lower level rectangularconfiguration 186 at the intersection of the pieces 178 b, 182 b and 178b, 184 b and 180 b, 182 b and 180 b, 184 b. The vibration isolators 198reduce or avoid the transmission of physical vibration or otherinfluences from the floor to the machine 30, further isolating suchdisturbances from adversely influencing the operation of the machine 30.The vertical space between the lower configuration 186 and theintermediate configuration 176 of the base support structure 172 isavailable to receive some of the components of the control system 120(FIGS. 25A and 25B), as well as the collection chamber 96 of the leadercollection subassembly 90 (FIGS. 1 and 3). Doors or panels (not shown)are attached to the pieces 178 a, 178 b, 182 a, 182 b, 184 a, 184 b andthe vertical supports 188 for the purpose of shielding the components onthe left, right and front sides of the base support structure 172 of themachine 30.

Left and right vertically extending upright beams 200 a and 200 b extendvertically at opposite rear corners at the intersections of pieces 180a, 182 a and 180 a, 184 a and 180 b, 182 b and 180 b, 184 b. The uprightbeams 200 a and 200 b extend considerably above the intermediate levelconfiguration 176 of the base support structure 172. A rectangular halostructure 202 extends forward from the upper ends of the upright beams200 a and 200 b. The halo structure 202 is formed by a front uppertransverse piece 178 c, a rear upper transverse piece 180 c, and leftand right upper longitudinal pieces 182 c and 184 c, which are locateddirectly above and oriented similarly to the corresponding pieces 178 a,180 a, 182 a and 184 a which form the intermediate-level configuration176. Braces 204 a and 204 b extend at an angle between the intersectionof the upright beam 200 a and the longitudinal piece 182 c and betweenthe intersection of the upright beam 200 b and the longitudinal piece184 c, respectively. The braces 200 a and 200 b support the halostructure 202 directly above the intermediate-level configuration 176.

As is shown in FIG. 1 and as understood from FIG. 11, the halo structure202 of the frame 42 supports linear arrays 118 a, 118 b and 118 c oflight receivers respectively attached to the front upper transversepiece 178 c and each of the left and right upper longitudinal pieces 182c and 184 c. Each linear receiver array 118 a, 118 b and 118 c receivesa multiplicity of individual aligned, parallel and closely spaced beamsof light which form the light curtain 117 (FIG. 1). The beams arecreated and focused upward by individual light emitters, such as LEDs,of linear arrays 119 a, 119 b and 119 c of light emitters. The linearlight emitter arrays 119 a, 119 b and 119 c are attached to theintermediate pieces 178 a, 182 a and 184 a at positions spaced closelyadjacent to the front, left and right edges of the granite slab 174(FIGS. 1-3). The linear light receiving arrays 118 a, 118 b and 118 cand the linear light emitting arrays 119 a, 119 b and 119 c create theconventional light curtain 117 (FIG. 1) between the front, left andright edges of the granite slab 74 and the halo structure 202. Shouldany one of the individual beams be broken by the insertion of a humanhand, for example, the machine 30 will immediately stop functioning. Thelight curtain 117 (FIG. 1) is a safety feature which prevents humaninjury and which prevents a foreign object from interfering with theoperations of the subassemblies of the machine 30. The spacing betweenindividual beams of light curtain 117 is less than the size of a humanhand, or a finger on a hand, or the anticipated size of an interferingforeign object. Suitable light receiving and emitting arrays 118 a-119c, and programmed instructions by which to create the light curtain 117,are available from Keyence Corporation of America, of Woodcliff Lake,N.J., USA.

The twist pin insertion subassembly 54 (FIGS. 2, 3 and 15) is notdirectly connected to the frame 42, but instead is connected to atransverse support beam 222. The transfer support beam 222 is connectedto the granite slab 174 by transversely spaced suspension brackets 224a, 226 a and 224 b, 226 b (FIG. 2). The suspension brackets 224 a and226 a are connected to one and of the support beam 222, and thesuspension brackets 224 b and 226 b are connected to the other ends ofthe support beam 222. The suspension brackets 224 a, 226 a and 224 b,226 b are connected on their bottom surfaces to the top surface of thegranite slab 174. In this manner, the beneficial inertialcharacteristics of the granite slab 174 are transferred to and from thesupport beam 222 and the twist pin insertion subassembly 54.

Preferably, the support beam 222 is formed of rigid extruded aluminumhaving the shape shown in FIG. 15 to avoid and minimize upward,downward, forward and backward reactive deflection in response tomovement of the twist pin insertion subassembly 54. Any movement of theinsertion head 56 (FIGS. 14 and 15) of the insertion subassembly 54 istransferred through the support beam 222 and the suspension brackets 224a, 226 a and 224 b, 226 b to the granite slab 174.

A transverse beam 228 extends between the vertically extending uprightbeams 200 a and 200 b, at a point located above the intermediate piece180 a and the upper piece 180 c. The transverse beam 228 supports thetwist pin pickup subassembly 44, as shown in FIGS. 1 and 2. Theorientation of the twist pin pickup subassembly 44 is generally inclinedat approximately a 45° angle from the horizontal, to facilitateextraction of the twist pins from the cartridge 50.

Twist Pin Pickup Subassembly

The cartridge 50 of the twist pin pickup subassembly 44 has a relativelylarge number of receptacles 240 formed over a receptacle area 241, asshown in FIG. 12. Each receptacle 240 is formed at a predetermined andestablished location. Each receptacle 240 contains one twist pin 34(FIG. 4). The cartridge 50 is connected to the XY positioning device 98in a predetermined and fixed location, thereby allowing the XYpositioning device 98 to move the cartridge 50 and place one receptacle240 at a time below the pickup head 46. Gas pressure is applied to thepickup head 46 to create a partial vacuum within the receptacle 240 toremove the twist pin from the receptacle 240. The gas pressure alsoconveys the twist pin removed from the receptacle 240 through thedelivery tube 52 to the twist pin insertion subassembly 54.

After the twist pin has been removed from the receptacle 240, thecontrol system 120 (FIGS. 25A and 25B) controls the XY positioningdevice 98 to move the cartridge 50 to locate another receptacle 240occupied by a twist pin 34 below the pickup head 46. After the priortwist pin has been assembled into the column of vias, the next twist pinis removed from the next receptacle 240 and is transported through thedelivery tube 52 to the insertion head 46 in the same manner. The XYpositioning device 98 continues moving the cartridge 50 in this manneruntil all of the twist pins necessary to assemble a circuit module havebeen removed from receptacles 240, or until all of the twist pins fromthe receptacles 240 of one cartridge 50 have been removed. When all ofthe twist pins from one cartridge have been used, the operation of themachine 30 ceases and the machine operator must then replace the emptycartridge 50 with a new cartridge 50 that is loaded with twist pins.Thereafter, the automated operation of the machine 30 continues toassemble the circuit module.

The cartridge 50 is shown in greater detail in FIG. 12. The cartridge 50includes a pallet plate 242 from which a handle 244 extends. By graspingthe handle 244, the entire cartridge 50 is manipulated. For example, thehandle 244 is used to place the cartridge 50 on the XY positioningdevice 98, and to remove the cartridge 50 from the XY positioning device98. The cartridge 50 is used to supply the twist pins to the twist pinpickup subassembly 44 and to store the twist pins until they are used.

The cartridge 50 is formed by at least one receptacle plate 246connected to and supported from the pallet plate 242. Four receptacleplates 246 are shown in FIG. 12 as forming the cartridge 50. All of thereceptacle plates 246 are basically identical in structure andconfiguration. All of the receptacle plates 246 include conventionalregistration and alignment posts 248 which hold the plates 246 instacked alignment with one another. The registration posts 248 alsoextend into the pallet plate 242, allowing the stacked receptacle plates246 to be held in a fixed relationship to the pallet plate 242. Theregistration posts 248 assure that the receptacle plates 246 and thepallet plate 242 maintain fixed relationships with one another.

Each receptacle 240 is formed by a vertically aligned series ofreceptacle holes formed in the receptacle plates 246. The receptacleholes are formed at the same predetermined locations in each receptacleplate 246. With the receptacle plates stacked and held in registeredalignment with one another by the registration posts 248, the receptacleholes in the receptacle plates 246 align with one another and create onetwist pin receptacle 240 which extends continuously through thereceptacle plates 246 from the upper surface (as shown) of the upperreceptacle plate 246 to the lower surface of the lower receptacle plate246. Each receptacle 240, like the receptacle holes which constituteeach receptacle 240, is formed at a predetermined and precisely definedlocation on the cartridge 50. The information defining the position ofeach individual receptacle 240 in the receptacle area 241 is used by thecontrol system 120 (FIGS. 25A and 25B) to move the XY positioning device98 and establish the location of each receptacle 240 below the pickuphead 46 (FIG. 13).

A relatively large number of receptacles 240 are typically located inthe receptacle area 241. The close spacing between the receptacles 240may result in as many as 10,000 receptacles in a receptacle area 241 ofapproximately 4 inches by 8 inches in size, under circumstances whereeach receptacle is 0.028 inches in diameter, for example. Differenttwist pin diameters may require different sizes of receptacles, and thesizes of the receptacles may adjust the number of those receptacles inthe receptacle area 241. Each of the receptacle plates 246 is preferablyformed of an aluminum alloy material having a vertical thickness ofapproximately 0.25 in. The number of receptacle plates 246 used in thecartridge 50 establishes the length of the receptacle. A fabricatedtwist pin having a length of approximately 0.5 in. will usually be aboutthe shortest length twist pin used. More typically, the length of thefabricated twist pin will be approximately 1.0, 1.5 or 2.0 inches inlength. Making each receptacle plate 246 with a thickness of 0.25 inchesallows two to eight receptacle plates to be stacked and registered bythe posts 248 on the pallet plate 242 to accommodate fabricated twistpins of the most-common lengths of 0.5-2.0 inches.

The receptacle holes formed in each receptacle plate 246 are best formedby drilling. Other types of hole formation techniques, such as laserdrilling, are usually incapable of penetrating a sufficient depth, andthe sidewalls are usually not as smooth and continuous as thosesidewalls formed by drilling. Limiting the vertical thickness of eachreceptacle plate 246 to approximately 0.25 in. facilitates drilling. Ashorter drill length offers a lesser risk of the drill deviatingtransversely from a desired axial path, and also permits the receptacleholes to be more quickly formed.

The pallet plate 242 is also preferably formed from an aluminum alloymaterial. A center area 249 (FIG. 3) of the pallet plate 242 underlyingthe receptacle area 241 is recessed below the lower surface of thelowermost receptacle plate 246. Because of the center recessed area 249of the pallet plate 246, a space 251 (FIG. 13) exists at the lower endof each receptacle 240, between the lower surface of the lowermostreceptacle plate 246 and the upper pallet plate 242. The space 251permits each receptacle 240 to vent from its bottom end as the twist pinis removed from the receptacle 240 by partial vacuum at the top end ofthe receptacle 240. This venting capability permits more effectiveremoval of each twist pin from its receptacle 240 by the pickup head 46(FIG. 13), as well as the transportation of the twist pin through thedelivery tube 52 to the pickup head 46 (FIGS. 1 and 2). This ventingcapability also allows the pickup head 46 (FIG. 13) to be verticallypositioned closely adjacent to the upper surface of the upper receptacleplate 246. A smaller space 253 (FIG. 13) between the pickup head 46 andthe upper receptacle plate 246 enhances the effectiveness of removingthe twist pin from the receptacle 240 using low pressure or partialvacuum.

The recessed center area 249 (FIG. 13) in the pallet plate 242 beneaththe receptacle area 241 also positions the twist pins in the receptacles240 with their leading ends 278 (FIG. 4) located slightly below theupper surface of the upper receptacle plate 246. Consequently, anyslight variation in length of the fabricated twist pins does not causethe leading end 78 of the leader 64 of the twist pin 34 (FIG. 4) toprotrude slightly above the cartridge 50. Because the twist pins 34 areinserted leader-first into the column 58 of vias 60, the twist pin mustbe inserted in each receptacle 240 with the leading end 78 of its leader64 located adjacent to the upper end of the receptacle 240 at the uppersurface of the upper receptacle plate 246. If the leading end 78 was toproject slightly above the upper surface of the upper receptacle plate246, the end of the twist pin might be inadvertently contacted and thetwist pin might be bent or distorted from its symmetrical configurationalong its axis (FIG. 4), when a cover 250 is attached to the upperreceptacle plate 246.

The cover 250 is attached to the upper receptacle plate 246 by thumbscrews 252. Holes 254 are formed in the cover 250 through which athreaded shaft of each thumb screw 252 extends. Threaded holes 256 areformed in the upper receptacle plate 246 in a position to align with theholes 254 in the cover 250. The threaded shaft of each thumb screw 252is threaded into the threaded hole 256 to hold the cover 250 in place ontop of the upper receptacle plate 246. Placing the cover 250 on top ofthe cartridge 50 after the receptacles 240 have been loaded with twistpins keeps the twist pins in the loaded position within the cartridgeand prevents dust and other foreign material from entering into thereceptacles 240 and adversely influencing the capability of removing anddelivering twist pins. When it is desired use the cartridge 50 in themachine 30, the cover 250 is removed.

In some circumstances, it is desirable to heat treat the twist pinsafter they are fabricated and before they are inserted in the columns ofaligned vias. Heat treating induces desirable mechanical characteristicsin the beryllium copper or other metal from which the twist pins areformed. By fabricating the pallet and receptacle plates 242 and 246 fromaluminum or other metal or ceramic material, the twist pins may be heattreated while residing in the cartridge 50. The cartridge 50 with loadedtwist pins is placed in an oven where the heat treatment occurs. Ofcourse, the cover 250 is removed during heat treatment.

For the XY positioning device 98 to position the receptacles 240precisely below the pickup head 46, the cartridge 50 must be retained ina fixed and predetermined location on an upper platform 258 of the XYpositioning device 98 (FIG. 2). To fix the cartridge 50 in position,guide rails 260 are attached to three sides of the pallet plate 242. Theguide rails 260 slide into correspondingly-shaped guide slots (notshown) formed on the upper platform 258 of the XY positioning device 98.The reception of the guide rails 260 into the guide slots (not shown)confines the cartridge 50 against movement in the plane of the upperplatform 258 of the XY positioning device 98. In addition, the uppersurface of the cartridge 50 is located at a predetermined and consistentheight relative to the upper platform 258. The position of the pickuphead 46 or the position of the upper platform 258 of the XY positioningdevice 98 is adjustable to accommodate different thicknesses of thecartridge 50 formed by different numbers of stacked receptacle plates246. The upper surface of the upper receptacle plate 46 over thereceptacle area 241 must also be coplanar with the plane of the upperplatform 258. Such a coplanar relationship maintains the same desiredvertical height of the pickup head 46 above the upper surface of theupper receptacle plate 246 over the receptacle area 241 as the XYpositioning device 98 positions each receptacle 240 for removal of atwist pin.

In addition to the upper platform 258 shown in FIG. 2, the XYpositioning device 98 includes the stepper motors 102 and 104 which movethe platform 258 in the front and back and the side to side directions.The stepper motors 102 and 104 are connected to conventional mechanicalmovement mechanisms (not shown) which transfer the rotational movementof the motors 102 and 104 into linear movement, thereby creating thefront and back and side to side movements of the upper platform 258necessary to position each receptacle 240 beneath with the pickup head46 (FIG. 13). The stepper motors 102 and 104 are rotated into precisepositions in response to control signals supplied by the control system120 (FIGS. 25A and 25B). In general, the XY positioning device 98 isconventional.

The stepper motors 102 and 104 achieve a high degree of precision inmoving the mechanical mechanisms of the XY positioning table 98.Consequently, a high degree of precision in both the X and the Ydimensions is available from the XY positioning device 98. This highdegree of precision allows each receptacle 240 of the cartridge 50 to beplaced directly below the pickup head 46 (FIG. 13), to extract a twistpin from each receptacle. As a twist pin is removed from each receptacle240, the control system 120 (FIGS. 25A and 25B) controls the motors 102and 104 to position another receptacle 240 containing a twist pin belowthe pickup head 46 to allow the next twist pin to be removed from thatreceptacle during the next assembly cycle.

The XY positioning device 98 and the cartridge 50 retained on theplatform 258 are oriented at a 45° angle to the horizontal, as shown inFIG. 2. The 45° angular orientation moves each twist pin to the lowercurved surface of each receptacle 240 due to the effects of gravity.Consequently, the twist pins are located in all of the receptacles 240at approximately the same location relative to an axis through eachreceptacle. The same positioning of the twist pins in the receptaclesfacilitates precise positioning of the pickup head 46 relative to thereceptacle to achieve the best removal effect. The 45° angle is alsoeffective in keeping the twist pins in the fully depressed position ineach receptacle 240, with the tail end 129 of each twist pin 34 (FIG. 4)located in contact with the recessed center area 249 of the pallet plate242 (FIG. 13). The downward gravity force on each twist pin in itsreceptacle prevents the leading ends 78 (FIG. 4) from extending beyondthe upper surface of the cartridge 50 and from interfering with thepickup head 46 during movement of the cartridge 50.

The pickup head 46 is supported over the receptacle area 241 by an arm262, as shown in FIGS. 2 and 13. One end of the arm 262 is rigidlyconnected to the pickup head 46 by use of a conventional clamp (notshown but understood from FIG. 13), and the other end of the arm 262 isconnected to a support plate 264 connected to the transverse beam 228 ofthe frame 42 (FIG. 11). The XY positioning device 98 is attached to thesupport plate 264. The arm 262 and the support plate 264 establish afixed position for the pickup head 46, and it is with respect to thisfixed position that the XY positioning device 98 moves the platform 258with the attached cartridge 50 to locate each receptacle 240 beneath thepickup head 46 (FIG. 13).

As shown in FIG. 13, the pickup head 46 includes a main body 266 and anozzle 268. The nozzle 268 is connected to the lower end of the mainbody 266 by a set screw 270. When connected together, the nozzle 268 andthe main body 266 defined a continuous, elongated and axially positionedpassageway 272 which extends from a pickup end 274 of the nozzle 268through an upper end 276 of the main body 266. The delivery tube 52 isconnected into the upper end 276 of the passageway 272 in the main body266 by a set screw 278.

The passageway 272 at the pickup end 274 has a diameter which isapproximately the same or slightly smaller than the diameter of areceptacle 240 in the cartridge. The passageway 272 at the pickup end274 is located in the most advantageous position relative to thereceptacle 240 to extract the twist pin. The most advantageous pickupposition can be slightly laterally offset from a coaxial relationship ofthe passageway 272 with the receptacle 240, because each twist pin willreside on the bottom curved side of the receptacle due to the 45°angular orientation of the cartridge 50, as described above.

The passageway 272 extends into a venturi chamber 280. A middle tube 282extends through the venturi chamber 282 and into the passageway 272 atthe lower (as shown) portion of the main body 266. The middle tube 282conveys the twist pins from the pickup end 274 of the passageway 272into the passageway 272 in the main body 266. The interior surface ofthe middle tube 282 smoothly continues the surface of the passageway 272extending from the pickup end 274, to avoid any discontinuity whichmight inhibit the upward movement of twist pins from the pickup end 274through the passageway 272.

Pressurized gas, typically air, is delivered from a gas source (706,FIG. 25B) to the venturi chamber 280 through a hose 285 connected to aninput fitting 284. The gas entering the venturi chamber 280 flows upwardaround the outside of the middle tube 282 due to the slightly largerinside diameter of the passageway 272 compared to the larger outsidediameter of the middle tube 282. The gas flow rate increases as it flowsaround the middle tube 282 due to a reduced cross-sectional size of thespace between the middle tube 282 and the passageway 272. When the gasexits from the space between the middle tube 282 and the passageway 272at the upper end (as shown) of the middle tube 282, a low pressure areais created adjacent to the upper end of the middle tube 282. This lowpressure is communicated downward through the middle tube 282 to createlow pressure or partial vacuum at the lower end of the middle tube atthe pickup end 274.

The low pressure at the pickup end 274 removes the twist pin from thereceptacle 240 of the cartridge 50, by lifting the twist pin through thepickup end 274 of the nozzle 268 and into the middle tube 282. Themomentum of the upward movement (as shown) of the twist pin through themiddle tube 282 propels it beyond the upper end of the middle tube 282,where the upward flowing gas at that location continues to transport thetwist pin upward in the passageway 272 and into the delivery tube 52.The gas flow continues through the delivery tube 252 while carrying thetwist pin, and the gas delivers the twist pin from the delivery tube 52into the insertion nozzle 57 of the insertion subassembly 54 (FIG. 14).

Vent holes 286 are formed transversely into the lower portion of thepassageway 272 in the nozzle 268 at the pickup end 274. The vent holes286 are formed with a predetermined configuration to vent some of thelow pressure to the ambient environment, thereby controlling the amountof force applied to remove the twist pins from the receptacles. Ventholes 288 are also formed in the main body 266 to intersect the middleportion of the passageway 272. The vent holes 288 vent some of thepressurized gas to the ambient environment. The venting through theholes 288 reduces back pressure at that location which has the effect ofincreasing the partial vacuum within the middle tube 282, therebyenhancing the capability of the partial vacuum to remove the twist pinfrom the receptacle.

The gas flow rate through the delivery tube 52 should be sufficient toassure that the twist pins are carried into the insertion nozzle 57. Anappropriate arrival speed of the twist pins at the via column 58 assistsin inserting the twist pins in the properly seated position (FIG. 10B).An excessively high delivery speed increases the possibility that thetwist pin will impact the upper via 60 of the column 58 with such forcethat the twist pins rebound out of the column 58. A relatively high rateof speed enhances the possibility of an occasional undesired deflectionof the twist pin from the column 58 or from a properly seated position,if the leading end 78 of the twist pin 34 inadvertently contacts theedge of an intermediate via in the column 58. The appropriate deliveryspeed of the twist pin facilitates the twist pin projecting cleanly intothe column 58.

The optical sensor 108 is incorporated in the pickup head 46. Theoptical sensor 108 is formed by a plurality of individual lightconducting optical fibers 290 and 292. The optical fibers 290 and 292form a conventional optic fiber bundle 294. The optical fibers 290 and292 are formed of conventional light transmissive material which has anindex of refraction that confines light within each of those fibers asthe light passes along the length of those fibers. The optical fiber 290is a center fiber in the bundle 294, and the other optical fibers 292are exterior fibers which surround the center fiber 290. An end 296 ofthe fiber bundle 294 is inserted into a receptacle 298 which has beenformed transversely into the main body 266 to intersect the passageway272. The end of 296 of the bundle 294 is held in the receptacle 260 by aretainer (not shown).

The optical fibers 290 and 292 are exposed at the end 296, and aretherefore capable of transmitting and receiving light from their exposedends. Light from a light source (not shown) is transmitted through thecenter optical fiber 290, and that light exits from the center opticalfiber 292 at the end 296 to illuminate the passageway 272. Light isreflected within the passageway 272 and is picked up and transmittedback to an optical transducer (742, FIG. 25B) connected to the exterioroptical fibers 292.

When a twist pin moves past the end 296 of the fiber bundle 294, thelight received by the exterior light fibers 292 at the end 296 ischanged by the passage of the twist pin. The changed characteristics ofthe light are sensed by the optical transducer, and the changed lightcharacteristics are detected as representing the passage of a twist pin.It is in this manner that the control system 120 (FIGS. 25A and 25B)uses the optical sensor 108 to detect the passage of a twist pin throughthe pickup head 46.

The delivery tubing 52 is formed from conventional metal hypodermictubing, which provides a uniform and smooth continuous interior surfaceto avoid creating obstructions or restrictions to the movement of thetwist pin.

Twist Pin Insertion Subassembly

The delivery tube 52 transports the twist pin 34 to the insertion head56 of the twist pin insertion subassembly 54, as shown in FIG. 14. TheXY positioning table 70 of the circuit module positioning subassembly 68(FIGS. 1-3) has previously located the circuit module 36 with a column58 of aligned vias 60 in a position to receive the twist pin 34 (FIG.10A). The twist pin 34 is conveyed from the delivery tube 52 into theinsertion nozzle 57, and the insertion nozzle 57 directs the twist pin34 along its axis 145 into the column 58 of aligned vias.

The insertion head 56 employs a delivery tube retention block 310 and anozzle retention block 312, both of which are connected to a mountingplate 314. The delivery tube 52 is retained in a bore 316 formed in theretention block 312 by a set screw 318. The nozzle 57, preferably formedfrom borosilicate glass, is retained in a bore 322 formed in the nozzleretention block 312, and is held in position by a set screw 324. Anentry end 326 of the nozzle 57 abuts the delivery end of the deliverytube 52. The entry end 326 of the nozzle 57 is angled divergentlyoutward to facilitate receiving the twist pin 34 as it travels from thedelivery tube 52 into the nozzle 57.

A center passage 328 of the nozzle 57 is smaller in diameter than theinside diameter of the delivery tube 52, so the angled entry end 326 isimportant in aligning the twist pin 34 with the axis 145 of the centerpassage 328. The diameter of the center passage 328 is slightly greaterthan the diameter of the bulges 84 of the twist pin 34 (FIG. 4), and thelength of the center passage 328 is longer than the distance between twoadjoining bulges 84. As a consequence of these relationships, the leader64 of the twist pin 34 becomes aligned coaxially with the axis 145 whenthe twist pin passes through the insertion nozzle 57. This coaxialalignment of the leader 64 facilitates inserting that leader into thecolumn 58 of aligned vias (FIG. 10B).

One of the benefits of forming the nozzle 57 from glass is that theglass resists wear caused by the friction of the twist pins movingthrough the nozzle 57. Glass also presents low friction to the movementof the twist pins. A glass nozzle 57 also allows the optical sensor 110to sense the passage of a twist pin through the insertion head 56 and todetermine whether the twist pin has been properly inserted in the column58 of aligned vias 60.

The optical sensor 110, like the optical sensor 108 described previouslyin connection with the pickup head 46 (FIG. 13), is also formed by aplurality of individual light conducting optical fibers 330 and 332. Theoptical fibers 330 and 332 form a conventional optic fiber bundle 334.The optical fibers 330 and 332 are formed of conventional lighttransmissive material with an index of refraction which confines lightwithin those fibers. The optical fiber 330 is a center fiber in thebundle 334, and the other optical fibers 332 become exterior fiberswhich surround the center fiber 330. An end 336 of the fiber bundle 334is inserted into a receptacle 338 which has been formed transverselyinto the nozzle retention block 312 to intersect the bore 322. The end336 is held in place in the receptacle 338 by a set screw 340. Theoptical fibers 330 and 332 are exposed at the end 336, and are thereforecapable of transmitting and receiving light from their exposed ends.

Light from a light source (not shown) is transmitted through the centeroptical fiber 330, and the light exits from the center optical fiber 330at the end 336 and projects through the glass insertion nozzle 57 toilluminate the center passage 328. Light is reflected within the centerpassage 328 and is picked up and transmitted back to an opticaltransducer (744, FIG. 25B) connected to the exterior optical fibers 332.The optical sensor 110 is located just below the position where thetapered entry end 326 transitions into the center passage 328 in theglass insertion nozzle 57.

When a twist pin moves through the glass insertion nozzle 57, the lightreceived by the exterior light fibers 332 at the end 336 is changed as aresult of the passage of the twist pin. The changed characteristics ofthe light are sensed and detected as representing the passage of a twistpin. In this manner, the control system 120 uses the optical sensor 110to detect the passage of a twist pin through the insertion head 56 andinto the column 58 of aligned vias.

The complete insertion of the twist pin 34 into a properly seatedposition in the column 58 of aligned vias (FIG. 10B) is further detectedby the optical sensor 110. When properly seated, the tail end 129 of thetwist pin 34 is located approximately transversely with respect to theend 336 of the fiber bundle 332, as shown in FIG. 14. The presence ofthe tail end 129 of the twist pin 34 at this location modifies theamount of light reflected to the optical fibers 332, compared to theamount of light reflected when the twist pin is not present at all inthe center passage 328 or when the twist pin is fully present in thecenter passage 328 as the twist pin passes through the insertion nozzle57. The light characteristics resulting from the presence of the tailend 129 of the twist pin 34 across from the end 336 of the opticalfibers 332 is detected to establish that the twist pin is properlyseated.

Although not shown in FIG. 14, the height of the optical sensor 110 maybe made adjustable in the retention block 312 to accommodate differentlengths of twist pins. Different length twist pins will result in thetail end 129 having a different height above the upper circuit board andwithin the center passage 328 when the twist pin is properly seated inthe via column 58. Alternatively, a different length insertion nozzle 57can be used for each different length of twist pin, with the length ofthe insertion nozzle correlated to the position of the optical sensor110 and the position of the tail end 129. In those circumstances wheredifferent length twist pins are assembled into a single circuit module,the height of the insertion head 56 can be moved vertically apredetermined amount after each longer twist pin is inserted to positionthe optical sensor 110 across from the tail end 129 of the longerinserted twist pin and thereby determine the seating condition of thetwist pin. After determining that the twist pin is properly seated, theinsertion head 56 may move the insertion nozzle 57 closer to the uppercircuit board of the module to insert the next twist pin in the next viacolumn in the next assembly cycle. This technique requires the insertionhead 56 to move up and down with each assembly cycle to determine theproperly seated position.

The optical sensor 110 is also capable of detecting the unusualcircumstance of a twist pin bouncing upward and out of its properlyseated position. The detection of the twist pin moving through theinsertion nozzle 57 occurs in the manner described. Thereafter, if thetwist pin is properly seated for a short time instant, the lightreflected from the tail end 129 of the twist pin 34 will indicate thatfact, for that short time instant. Then, if the twist pin rebounds orbounces from its properly seated position, the light reflected will besimilar to that of the twist pin passing through the nozzle 57 duringinitial insertion. This difference in light characteristics and thetiming or sequence of those characteristics indicates that the twist pinhas bounced from its properly seated position.

A similar situation exists if the twist pin 34 does not seat properly,as might occur if the leading end 78 happens to hang up on one of thevias 60 in the column 58, rather than passing completely through thecolumn 58 (not shown but understood from FIGS. 10A and 10B). Under thiscircumstance, the tail end 129 of the twist pin stops above the locationof the end 336 of the fiber bundle 334, and the resulting optical signalwill present light conditions similar to the continuous presence of thetwist pin in front of the optical sensor 110. This condition isrecognized as an improper insertion condition of the twist pin.

Under conditions of an improperly seated twist pin, one or more attemptsto automatically seat the initially improperly seated twist pin areperformed. These attempts involve delivering pulses or short blasts ofpressurized gas through the delivery tube 52. The pulses of pressurizedgas are introduced at the pickup head 46 of the pickup subassembly 44,in the manner previously described in connection with FIG. 13. Asunderstood from this previous description, the pressurized gas flowsthrough the delivery tube 52 and into the insertion nozzle 57. Thepassage of the pulse of gas may be successful in disturbing or movingthe improperly seated twist pin, and causing it to move into a properlyseated position. The optical sensor 110 determines if and when the twistpin 34 becomes properly seated by sensing the light characteristics whenthe tail end 129 of the twist pin 34 is directly across from the end 336of the optical fiber bundle 334. If the delivery of gas in this mannerdoes not establish the proper seating of the twist pin after a number ofsuch attempts, the control system 120 (FIGS. 25A and 25B) ceasesoperation of the machine 30 and the machine operator is notified of thenecessity to remedy the problem.

The optical camera 116 is connected to the mounting plate 314 of theinsertion head 56 with an attachment bracket 342, as shown in FIG. 14.The optical camera 116 views images along an optical axis 344. Theoptical axis 344 is oriented parallel to, and is offset a predetermineddistance from, the axis 145 of the insertion nozzle 57. The optical axis344 is precisely defined and used to establish the location of thefiducials 144 on the circuit modules 36 (FIGS. 9A and 9B). Using thefiducials 144 allows the expected locations of the vias 60 of thecolumns 58 to be established. The hole drilling map information iscorrelated to the location of the fiducials 144. Locating the fiducials144 on the circuit module allows the hole drilling map information to becoordinated with the expected location of the upper via 60 in eachcolumn 58 in the circuit module, as established by the movement of theXY positioning table 70 relative to the axis 145 through the insertionnozzle 57.

The optical camera 116 is used with a conventional optical recognitionsoftware program to determine whether the actual location of the column58 of vias 60 on the circuit module 36 deviates from the expectedlocation defined by the hole drilling map information. Such a deviationcould occur during the process of manufacturing each printed circuitboard 32 if the holes drilled during manufacturing of the printedcircuit boards 32 were not precisely in the positions defined by thehole drilling map information. To evaluate the actual position of eachvia column 58, the XY positioning table 70 moves the circuit module tolocate the via column in the expected position of the upper via 60relative to the optical axis 344. The optical recognition software thendetermines the optical center of the via column 58 based on theintensity and pattern of light received by the camera 116. Upondetecting that the optical center of the upper via 60 is not preciselyat the location expected from the hole drilling map information, theoptically determined actual center location of the via column is used tomodify the hole location coordinates obtained from the hole drilling mapinformation. This modified hole location is used when inserting a twistpin in the via column 58; the XY positioning table 70 moves the circuitmodule to locate the actual center of the via column 58 in alignmentwith the axis 145 of the insertion nozzle 57. The modified hole positionobtained in this manner facilitates the successful insertion of eachtwist pin.

In addition to the capability of determining the actual center of eachvia column 58, the camera 116 and its associated optical recognitionsoftware have the capability of identifying any obstructions that mightbe present in the column 58 of aligned vias. Obstructions present in thecolumn 58 are recognized by the pattern and intensity of the lightpassing through the column 58 and viewed by the camera 116. Furtherstill, the camera 116 and its associated optical recognition softwarehave the capability of determining whether the vias 60 in the via column58 are aligned sufficiently to allow a twist pin to be successfullyinserted. The alignment is also evaluated from the pattern and intensityof light viewed by the camera 116.

Any column 58 of vias 60 which is obstructed or which is sufficientlymisaligned so that a twist pin is unlikely to be successfully insertedis identified, the coordinates of that column are added to a skip list,and no twist pin is attempted to be inserted in the column. The controlsystem 120 (FIGS. 25A and 25B) uses the skip list to not insert twistpins in those columns. After assembling twist pins in all of the columns58 other than those obstructed or misaligned columns, the machineoperator is provided with the skip list information. This informationwill allow the operator to determine whether a twist pin can be insertedmanually, or whether the circuit module must be discarded.Alternatively, the columns on the skip list could be identified to themachine operator before assembly cycles are performed, to allow themachine operator to evaluate and override determinations of thosecolumns on the skip list.

Optically determining the position, obstruction and alignment of eachcolumn of vias is preferably executed as a continuous process in whichall of the columns 58 of aligned vias are scanned by moving each column58 beneath the optical axis 344 of the camera 116 before any twist pinsare inserted. Alternatively, the same information may be obtainedsimultaneously while performing assembly cycles. The preciserelationship of the optical axis 344 of the camera 116 and the axis 145of the insertion nozzle 57 allows the camera 116 to scan and evaluatecolumns 58 of vias for position, obstructions and alignment in advanceof inserting the twist pins. A look-forward type of scanning is requiredunder these circumstances, and information concerning each column 58 isdetermined one or more assembly cycles in advance of assembling thetwist pin in that column 58.

Depending upon the relative locations of the axes 145 and 344, it may benecessary for the XY position table 70 to move and stop intermittentlybetween each optical scanning position and each twist pin insertionposition, when the via columns are evaluated simultaneously withassembling the twist pins in the via columns 58. Moving directly fromone insertion position to another insertion position may not bepossible, without stopping at or backtracking to an optical scanningposition. Such movement could slow the assembly process, and it is forthis reason that optically scanning all of the columns 58 of vias beforecommencing the insertion of the twist pins is beneficial in mostcircumstances. If all of via columns 58 are optically scanned forposition, obstructions and alignment beforehand, the optical camera 116is not used during the twist pin insertion process, because all of theinformation obtained from previously scanning all of the columns of viaswill have already created the skip list and established the coordinatesof the actual centers of the via columns 58.

To ensure that sufficient light is projected upwardly through thecolumns 58 of vias 60, three racks 346 of high intensity lights 348 arelocated on the upper surface of the granite slab 174 beneath the circuitmodule 36 and surrounding the grip and cut subassembly 74 and thelongitudinal movement subassembly 80, as shown in FIGS. 3 and 17. Thelights 348 are preferably light emitting diodes (LEDs), and those LEDsare directed to project a substantial amount of their light upwardtoward the circuit module 36 connected to the pallet 146 (FIG. 17). Theamount of upward projected light from the light racks 346 assures thatenough light will pass upward through each column 58 of vias to allowthe optical camera 116 and its associated optical recognition softwareto determine the actual center position of the via column 58, todetermine the presence of an obstruction in the column 58, and todetermine whether the column 58 is sufficiently aligned to automaticallyaccept a twist pin.

Conventional optical recognition software is used to evaluate thecolumns 58 of vias 60 for position, obstruction and alignment. Onesuitable optical recognition software package usable for these purposesis a Visionscape® GigE Machine Vision System which is commerciallyavailable from Microscan Solutions, Inc. of Renton, Wash., USA. A camera116 suitable for use with this optical recognition software is aVisionscape® GigE CameraUXGA Mono CCD, also available from MicroscanSolutions, Inc. of Renton, Wash., USA.

The twist pin insertion subassembly 54 provides the capability tovertically move the insertion head 56 relative to the circuit module 36,as is shown in FIG. 15. The insertion subassembly 54 includes the linearmotor 72 located in a housing 352 which is connected to the transversesupport beam 228 (FIGS. 2 and 15). The linear motor 72 is connectedwithin the housing 352 to raise and lower a mounting pad 354 located onthe exterior of the housing. The mounting plate 314 of the insertionhead 56 is connected to the mounting pad 354. Movement created by thelinear motor 72 therefore raises and lowers the insertion head 56. Amongother things, the ability to raise and lower the insertion head 56allows the insertion nozzle 57 to be moved vertically to avoid contactwith circuit components 40 located on the upper surface of the uppercircuit board 32 of the module (FIGS. 9A and 9B) during movement of thecircuit module 36 by the circuit module positioning subassembly 68, ifthe twist pins are inserted after the components 40 are connected to thecircuit board.

As shown in FIG. 15, the mounting plate 314 is connected to the mountingpad 354 by fasteners such as screws 356. The mounting pad 354 is locatedat the exterior of the housing 352. One illustrative and exemplaryconnection of the mounting pad 354 to the linear motor 72 is shown inFIG. 15. The mounting pad 354 is connected by posts 358 to an L-shapedbracket 360 which is located within the interior of the housing 352. Theposts 358 extend through and move along vertical slots 361 in thehousing 352. The L-shaped bracket 360 is connected to a shaft 362 of thelinear motor 72. Operation of the linear motor 72 extends or retractsthe shaft 362 relative to a casing 364 of the motor 72. A linear slide(not shown) in a casing 364 of the motor 72 supports the shaft 362 sothat it moves precisely linearly without significant transversedeflection. Extension of the shaft 362 lifts the L-shaped bracket 360within the housing 352, and causes the posts 358 to move along thevertical slots 361 in the housing 352 while simultaneously transferringthe vertical upward movement to the mounting pad 354 and the attachedinsertion head 56. Retraction of the shaft 362 of the motor 72 causesthe opposite downward movement.

The linear motor 72 and its associated internal connection mechanismswithin the housing 352 are conventional and available commercially fromSMAC of Carlsbad, Calif., USA. Its basic functions are summarized asfollows. Inside the motor casing 364, a main body 366 is connected tothe shaft 362. A moving electromagnetic coil 368 is attached to the mainbody 366, and the coil 368 surrounds a linear permanent magnet 370.Current conducted through the moving coil 368 creates a magnetic fieldwhich interacts with the magnetic field of the permanent magnet 370.This interaction creates a movement force which is transferred from themoving coil 368 to the main body 366 to move the shaft 362. The degreeand extent of movement is directly related to the current conducted bythe moving coil 368. It is in this manner that electrical signalsapplied to the linear motor 72 cause the shaft 362 to extend and retractand the mounting pad 354 to move vertically.

The extent of movement of the shaft 362 is measured by a linear encoder372. The linear encoder 372 includes a linear measurement track 374 anda sensor 376. The linear measurement track 374 has markings orindications formed at precise and definite intervals along its length.The markings or indications of the track 374 are sensed by the sensor376, and the signals from the sensor 376 indicate the position of theshaft 362. The position of the sensor 376 relative to the track 374establishes the position of the shaft 362. The position of the shaft 362is correlated to the position of the insertion head 56, and specificallythe lower end of the insertion nozzle 57. In this manner, the verticalposition of the insertion nozzle 57 is controlled.

Based on the information available from the linear encoder 372, theupward and downward movement of the insertion head 56 allows theinsertion nozzle 57 to be positioned relative to the upper printedcircuit board 32 of the circuit module 36, as shown in FIG. 14. Locatingthe lower end of the insertion nozzle 57 at a predetermined spacing 377relative to the upper printed circuit board 32 establishes the bestconditions for conveying the twist pin from the pickup head of thepickup subassembly through the delivery tube 52 to the insertion head56. If the spacing 377 between the lower end of the insertion nozzle 57and the upper printed circuit board 32 is too small, enough backpressure to the gas flow through the delivery tube 52 is created toimpede the delivery of the twist pin. If the spacing 377 between thelower end of the insertion nozzle 57 and the upper printed circuit board32 is too large, there is an increased possibility that the leading end78 of the twist pin 34 will deviate from a direct projection into thecolumn 58, but will instead deflect laterally from an edge of the uppervia 60 in the column and create an impediment to the successfulinsertion of the twist pin and to the continued automated operation ofthe machine 30.

The vertical height of the upper printed circuit board 32 of the circuitmodule 36 is established for use by the movement of the linear motor 72by the control system 120 (FIGS. 25A and 25B). This position isestablished with each circuit module 36 into which twist pins areinserted because there may be slight differences in height amongdifferent circuit modules 36 of the same type, due to manufacturingdifferences or slight differences in the connection position of eachcircuit module 36 on the pallet 146 (FIG. 1). Signals supplied to thelinear motor 72 cause it to raise the insertion head 56 to an uppermostposition, where it is assured that the lower end of the insertion nozzle57 will clear any electronic circuit components 40 connected to theupper printed circuit board 32 of the module 36 (FIGS. 9A and 9B).Thereafter, the linear motor retracts the shaft 362 causing theinsertion head 56 to move downward. The downward movement commences at amore rapid rate and then diminishes. When the lower end of the insertionnozzle 57 contacts the upper via 60 of a column 58, the current drawn bythe moving coil 368 of the motor 72 increases due to the addedmechanical resistance to the continued movement of the motor shaft 352.The increase in current is recognized by a current sensor (not shown)associated with the moving coil 368 and the position sensed by thelinear encoder 372 is correlated to this increase in current. Thisposition defines the upper surface of the upper circuit board of thecircuit module.

To position the nozzle 57 for the most effective delivery of the twistpins, the linear motor 72 elevates the lower end of the insertion nozzle57 above the printed circuit board by the predetermined spacing 377which achieves the best transfer and insertion characteristics of thetwist pins into the column 58 of aligned vias 60. To raise the insertionhead 56 and the nozzle 57 to a greater height which will avoidelectronic components 40 on the upper circuit board of the module,component parameter information is used by the control system 120 (FIGS.25A and 25B). The component parameter information defines the height,location and orientation of circuit components relative to the uppersurface of the upper circuit board of the circuit module. This heightparameter information is thereafter used to lift the insertion nozzle 57sufficiently to avoid the circuit components 40 as the XY positioningtable 70 moves the circuit module for the insertion of twist pins ineach column 58 of aligned vias.

The delivery tube 52, the optical bundle 334, and electrical conductors380 connected to the camera 116, are sufficiently flexible to permit theupward and downward movement of the insertion head 56 without binding orcreating a significant restriction. The cross-sectional configuration ofthe transverse support beam 222 resists deflection in response to thereaction forces arising from rapid vertical movement of the linear motor72. The resistance from the transverse support beam 222 keeps the lowerend of the insertion nozzle 57 at the desired spacing from the uppercircuit board of the circuit module. The linear motor 72 is connected inthe housing 352 by fasteners (not shown), and the housing 352 isconnected to the beam 222 by suitable fasteners, such as screws 378. Thebeam 222 is connected to the granite slab 174 by the suspension brackets224 a, 226 a and 224 b, 226 b (FIGS. 1-3), so the reactive forcestransferred to the beam 222 by the movement of the insertion head 56 areresisted by the inertia of the granite slab 174.

The insertion head 56 moves the insertion nozzle 57 and the opticalcamera 116 vertically along their axes 145 and 344, respectively. Nolateral or transverse movement of the insertion nozzle 57 and the camera116 occurs with respect to their axes 145 and 344. The circuit modulepositioning subassembly 68 achieves the lateral or transverse movementof the circuit module in the horizontal plane relative to the axes 145and 344.

Circuit Module Positioning Subassembly

The XY positioning table 70 of the circuit module positioningsubassembly 68 moves the circuit module 36 to locate a column 58 of vias60 coaxially with the twist pin insertion axis 145 and the optical axis344. Each circuit module 36 is attached in a rigid position relative tothe pallet 146, and the pallet 146 is connected rigidly to the XYpositioning table 70. Signals from the control system 120 (FIGS. 25A and25B) cause the XY positioning table 70 to move in both the X and Yhorizontal directions.

The XY positioning table 70 is shown in FIGS. 2 and 3. The XYpositioning table 70 includes an upper table structure 390 which movesin the X and Y horizontal directions. The upper table structure 390 hasan open aperture 392 through which the grip and cut subassembly 74 movesupward relative to the lower printed circuit board of the circuitmodule, when the leader 64 of the twist pin 34 is gripped, pulled andcut and the severed leader 64 is extracted (FIGS. 10C-10H). The uppersurface of the upper table structure 390 is planar. Conventionalregistration devices (not shown), such as registration pins, hold thepallet 146 in a fixed predetermined position on the upper tablestructure 390.

The XY positioning table 70 also includes an intermediate tablestructure 394 which moves in only one of the X or Y directions. As shownin FIGS. 2 and 3, the intermediate table structure 394 moves only in theforward and backward direction. The upper table structure 390 isoperatively connected to the intermediate table structure 394 and moveslaterally left and right relative to the intermediate table structure394.

The intermediate table structure 394 moves on a pair of spaced apartlinear tracks 396. The tracks 396 are attached to a bottom plate 398,and the bottom plate 398 is attached to the upper surface of the graniteslab 174. The upper surface of the granite slab 174 is ground to a highprecision planar surface. The upper and lower surfaces of the bottomplate 398 are planar surfaces which are precisely coplanar with oneanother. The tracks 396 are identical in cross-sectional configurationto one another, and are attached to the upper planar surface of thebottom plate 398 so that the tracks 396 extend precisely parallel withone another. Bearings (not shown) are attached to the bottom surface ofthe intermediate table structure 394 to contact and move along each ofthe tracks 396, and to support the intermediate table structure 394 fromthe tracks 396. The top and bottom surfaces of the intermediate tablestructure are planar surfaces which are precisely coplanar with oneanother. A precision linear motor 100 (also see FIG. 25A) is associatedwith each track 396. The motor 100 is responsive to signals from thecontrol system 120 (FIG. 25A) to move the intermediate table structure394 in precise forward and backward directions relative to thestationary bottom plate 398 and granite slab 174.

The upper table structure 390 moves on a pair of spaced apart lineartracks 402. The tracks 402 are attached to the intermediate tablestructure 394. The upper and lower surfaces of the upper table structure304 are planar surfaces which are precisely coplanar with one another.The tracks 402 are identical in cross-sectional configuration to oneanother, and are attached to the upper planar surface of theintermediate table structure 394 so that the tracks 402 extend preciselyparallel with one another. Bearings (not shown) are attached to thebottom surface of the upper table structure 390 to contact and movealong each of the tracks 402 and to support the upper table structure390 from the intermediate table structure 394. A precision linear motor101 (also see FIG. 25A) is associated with each track 402. The motor 101is responsive to signals from the control system 120 (FIG. 25A) to movethe upper table structure 390 in precise left and right lateraldirections relative to the intermediate table structure 394 as well aswith respect to the stationary bottom plate 398 and granite slab 174.

The intermediate table structure 394 and the bottom plate 398 alsoinclude center apertures 406 and 408 similar to the aperture 392 in theupper table structure 390. The center apertures 392 and 406 aresufficiently large to remain clear of contact with the grip and cutsubassembly 74 during movement of the upper and intermediate tablestructures 390 and 394. Signals supplied to the motors 100 and 101 causethe precise movement of the intermediate and upper table structures 394and 390, respectively, thereby moving the pallet 146 and the attachedcircuit module 36 into precise positions in which the centers of thecolumns 58 of vias 60 are located substantially coaxially with the axis145 of the insertion nozzle 57 and the optical axis 334 of the camera116 (FIG. 14), as previously described.

The XY positioning table 70 and the software programs for operating itsmotors are commercially available from Aerotech, Inc. of Pittsburgh,Pa., USA.

Grip and Cut Subassembly

The grip and cut subassembly 74, shown in FIGS. 16-23, operates relativeto the axis 145 through the insertion nozzle 57 (FIG. 14). The grip andcut subassembly 74 is connected to a shaft 420 of the linear/rotationalmotor 82 of the longitudinal movement subassembly 80. Thelinear/rotational motor 82 is connected to a bracket 422, as shown inFIGS. 16 and 17. An upright piece 424 of the bracket 422 is connected tothe linear/rotational motor 82. A transverse piece 426 is connected tothe upright piece 424. The transverse piece 426 is connected to thegranite slab 174, at one edge of the center opening 428 formed in thegranite slab 174. The position of the linear motor where connected tothe bracket 422, and the position of the bracket 422 square connected tothe granite slab 174, locates the shaft 420 of the motor 82 coaxiallywith the axis 145. Consequently, the linear extension and retraction ofthe shaft 420, and the rotation of the shaft 420, maintains the cuttingwedges 154 and 156 (FIGS. 10C-10H) of the pinch and cut blade 76 coaxialwith respect to the axis 145.

The principal function of the grip and cut subassembly 74 is to move thepinch and cut blade 76 so that its cutting wedges 154 and 156 grip theleader 64 by pinching it so that the leader 64 can be pulled andthereafter cut or severed (FIGS. 10C-10H). To accomplish theseoperations, the grip and cut subassembly 74 includes the pinch and cutblade 76, a blade deflecting mechanism 440 which interacts with thepinch and cut blade 76 to move the jaw members 150 and 152 and cuttingwedges 154 and 156 toward and away from one another, and a bladeactivator 442 which moves the blade deflecting mechanism 440 relative tothe pinch and cut blade 76 to move the jaw members 150 and 152 towardand away from one another, as shown in FIGS. 16, 18 and 19.

The blade activator 442 is preferably of a conventional piston andcylinder construction, in which a piston 444 moves longitudinally withina cylinder 445 of a cylinder body 446 of the blade activator 442, asshown in FIGS. 18 and 19. A hollow connection rod 448 is connected at arear end to the piston 444, and a front end of the connection rod 448 isconnected to the blade deflecting mechanism 440. The connections arepreferably threaded connections. Pressurized gas is delivered throughhoses 450 and 452 to the blade activator 442 to move the piston 444longitudinally forward and backward within the cylinder 445 of thecylinder body 446, respectively. The movement of the piston 444 istransferred through the connection rod 448 to the blade deflectingmechanism 440. The pinch and cut blade 76 is positioned stationarily,and the forward and backward movement of the blade deflecting mechanism440 relative to the blade 76 moves the jaw members 150 and 152 into andbetween the opened, closed and partially closed positions shown in FIGS.21, 23 and 22, respectively.

A blade support bracket 454 connects to and extends longitudinallyforward from the cylinder body 446. A retainer pin 456 extends though ahole 458 in a front end of the support bracket 454. A reduced-diameterportion of the pin 456 extends through the hole 458 beyond the supportbracket 454 and fits into a hole 460 in a rear end web portion 462 ofthe blade 76. In this manner, the blade 76 is connected to a forward endof the blade support bracket 454 in a stationary longitudinal positionrelative to the cylinder body 446. However, the pin 456 permits theblade 76 to pivot in a plane perpendicular to an axis through the pin456.

As shown in FIGS. 21-23, the pinch and cut blade 76 is formed as anintegral single-piece structure, preferably of resilient spring steel orhigh-speed (tool) steel. The web portion 462 joins the jaw members 150and 152 at a rear end of the blade 76. The retainer pin 456 in the hole460 holds the pinch and cut blade 76 stationary. The jaw members 150 and152 are generally symmetrically positioned on opposite sides of thecenter axis 145. The jaw members 150 and 152 extend longitudinallyforward and transversely outwardly from the web portion 462 and the axis145. The jaw members 150 and 152 are separate from one another exceptwhere they integrally join the blade 76 at the web portion 462. The webportion 462 is transversely offset from the center axis 145 to avoidcontacting the conduction tube 162 (FIG. 19).

Exterior surfaces 464 and 466 of the jaw members 150 and 152,respectively, are smooth and generally symmetrical with respect to thecenter axis 145. The exterior surfaces 464 and 466 are contacted byroller bearings 465 and 467, respectively, of the blade deflectingmechanism 440 to cause the jaw members 150 and 152 to deflect toward andaway from one another. The strength and resiliency of the material fromwhich the blade 76 is made causes the jaw members 150 and 152 to reboundback away from one another when the force from the blade deflectingmechanism 440 is relieved.

Shoulders 468 and 470 extend integrally from the inside surfaces of thejaw members 150 and 152, respectively, along a portion of the length ofeach jaw member 150 and 152. The shoulders 468 and 470 extend toward oneanother across the space between the jaw members 150 and 152. Theshoulders 468 and 470 reinforce each of the jaw members 150 and 152 andcontact one another to prevent the cutting wedges 154 and 156 from beingoverdriven into contact with one another when the jaw members are movedto the closed position (FIG. 23). The overdrive protection from theshoulders 468 and 470 prevent chipping and premature wear of the cuttingwedges 154 and 156. The shoulders 468 and 470 are also transverselydisplaced from the center axis 145 (FIG. 19) to avoid interfering withthe leader 64 or the conduction tube 162, when the jaw members 150 and152 are closed.

The forward ends of the jaw members 150 and 152 curve longitudinallyforward and transversely inward toward one another and terminate at thecutting wedges 154 and 156. The cutting wedges 154 and 156 are made ofhardened sharpened material. The jaw members 150 and 152 bring thecutting wedges 154 and 156 toward one another to sever the leader 64(FIG. 10G) or to pinch the leader 64 without severing it (FIGS. 10C-10E)whenever a transverse inward force is applied by the roller bearings 465and 467 of the blade deflecting mechanism 440 to force the jaw members150 and 152 toward one another.

As shown in FIGS. 18, 19, 21-23, the blade deflecting mechanism 440includes a clevis 472 which is connected to the forward end of theconnection rod 448. The U-shaped body which defines the clevis 472projects forward away from the connection rod 448, and defines an openspace 474 in the center of the clevis 472. The pinch and cut blade 76 ispositioned within the open space 474. A bearing plate 476 is connectedto the clevis 472 on one transverse side of the open space 474. Anelongated slot 478 (FIG. 18) is formed in the bearing plate 476 toreceive the retainer pin 456. The elongated slot 478 permits the bearingplate 476 and the clevis 472 to move forward and backward with respectto the stationary retainer pin 456 as the blade deflecting mechanism 440moves forward and backward. A wedge plate 480 is connected to the clevis472 on the opposite transverse side of the open space 474 from thebearing plate 476. The bearing plate 476 and the wedge plate 480 supportand retain the pinch and cut blade 76 between their opposing facingsurfaces within the open space 474.

The roller bearings 465 and 467 connect to the forward ends of theclevis 472 at forward locations in the space 474. The roller bearings465 and 467 contact the exterior surfaces 464 and 466 of the jaw members150 and 152, respectively. The exterior surfaces 464 and 466 extendforward and transversely outward. The exterior surfaces 464 and 466 aresymmetrical about the center axis 145. Forward longitudinal movement ofthe clevis 472 forces the roller bearings 465 and 467 to roll forwardalong the exterior surfaces 464 and 466 of the jaw members 150 and 152,respectively. The jaw members 150 and 152 deflect more closely togetheras the roller bearings 465 and 467 move forward along the exteriorsurfaces 464 and 466. In a similar manner, rearward longitudinalmovement of the clevis 472 moves the roller bearings 465 and 467rearward along the exterior surfaces 464 and 466, and the resiliency ofthe material from which the blade 76 is formed moves the jaw members 150and 152 outwardly away from one another. With the blade deflectingmechanism 440 moved to its most rearward position, a slight clearanceexists between the exterior surfaces 464 and 466 and the roller bearings465 and 467, allowing the jaw members 150 and 152 to separate fully inthe open position (FIG. 21).

More details concerning the blade activator 442 are shown in FIGS. 18and 19. The cylinder body 446 defines the cylinder 445 within which thepiston 444 moves. The cylinder 445 extends from a front end of thecylinder body 446 to a rear end of the body 446. The piston 444 has anexterior diameter that allows it to fit within the cylinder 445.Longitudinally spaced annular grooves in the piston 444 receive sealingrings 494 and 496 which seal the piston 444 within the cylinder 445. Afront cylinder cap 498 is attached to the front end of the cylinder body446, and a rear cylinder cap 500 is attached to the rear end of thecylinder body 446. The piston 444 moves within the cylinder 445 betweenthe front and rear cylinder caps 498 and 500.

The front cylinder cap 498 has a generally square connection flange 502with a rearward extending cylindrical projection 504. The connectionflange 502 is attached to the front end of the cylinder body 446 withscrews 506. The cylindrical projection 504 has an exterior diameter thatis slightly smaller than the interior diameter of the cylinder 445. Withthe flange 502 attached to the cylinder body 446, the cylindricalprojection 504 extends rearwardly into the cylinder 445 from the frontend of the cylinder body 446. A sealing O-ring 508 fits within anannular recess formed in the exterior of the cylindrical projection 504,and the sealing O-ring 508 establishes a seal between the front cap 498and the cylinder body 446 within the cylinder 445.

The front cylinder cap 498 has a front bore 512 through which theconnecting rod 448 extends. A front rod seal 514 is positioned within aninside annular groove formed in the front bore 512 and contacts theexterior surface of the connecting rod 448. The front rod seal 514establishes a seal around the connecting rod 448 where it exits from thefront cylinder cap 498. A rear end of the connecting rod 448 connects tothe piston 444 within the cylinder 445. In this manner, longitudinalforward and backward movement of the piston 444 within the cylinder 445is transferred through the connecting rod 448 to the blade deflectingmechanism 440.

The rear cylinder cap 500 has a generally square connection flange 518with a forward extending cylindrical projection 520. The connectionflange 518 is attached to the rear end of the cylinder body 446 withscrews 522. The cylindrical projection 520 has an exterior diameter thatis slightly smaller than the interior diameter of the cylinder 445. Withthe flange 518 attached to the cylinder body 446, the cylindricalprojection 520 extends forward into the cylinder 445 from the rear endof the cylinder body 446. A sealing O-ring 524 fits within an annularrecess formed in the exterior of the cylindrical projection 520, and thesealing O-ring 524 establishes a seal between the rear cap 500 and thecylinder body 446 within the cylinder 445.

The rear cylinder cap 500 has a rear bore 528 through which a hollow rodextension 530 extends. A rear rod seal 532 is positioned within aninside annular groove formed in the rear bore 528 and contacts theexterior surface of the rod extension 530. The rear rod seal 532establishes a seal around the rod extension 530, where the rod extension530 exits from the rear cylinder cap 500. A front end of the rodextension 530 connects by threads to the rear side of the piston 444within the cylinder 445 of the cylinder body 446. In this manner, therod extension 530 moves longitudinally forward and backward with thecorresponding movement of the piston 444 within the cylinder 445. Therear end of the rod extension 530 extends rearwardly from the rear cap500, is centered generally about the center axis 145 and extends to thecut and pull subassembly 80 into the hollow shaft 420 of thelinear/rotational motor 82 (FIG. 16).

The connecting rod 448 is hollow, and thereby defines an interiorpassageway through the rod 448. A central hole 538 is formed through thepiston 444 in alignment with the hollow interior of the connecting rod448. The rod extension 530 is hollow, and thereby defines an interiorpassageway through the rod extension 530. The clevis 472 has a hole 540formed through it in alignment with the hollow interior of theconnecting rod 448. In this manner, an unobstructed internal passagewayextends through the hole 540 in the clevis 472, the hollow interior ofthe connecting rod 448, the central hole 538 of the piston 444, andhollow interior of the rod extension 530. This unobstructed internalpassageway is coaxial with the axis 145, and the conduction tube 162 islocated therein.

The conduction tube 162 conducts the severed leaders 64 away from thecut and pinch blade 76 of the grip and cut subassembly 74. A forward endof the conduction tube 162 is positioned concentric with the center axis145 in the space between the jaw members 150 and 152. The forward end ofthe conduction tube 162 is slightly flared to direct the leading end 78of the leader 64 into the conduction tube 162, to ensure that thesevered leader 64 enters and is transported through the conduction tube162. The conduction tube 162 is connected to move in unison with theblade deflecting mechanism 440, the connection rod 448, the piston 444and the rod extension 530, by an adhesive applied between the conductiontube 162 and the inside the hollow connection rod 440.

Fluid passageways 544 and 546 are formed forward from the rear end ofthe cylinder body 446, and the passageways 544 and 546 open into thecylinder 445 at positions which are at the rear and front of the piston444, respectively, as shown in FIG. 20. The passageways 544 and 546provide a sealed path through the cylinder body 446 and into thecylinder 445. Conventional hose fittings 548 are attached to the rearend of the cylinder body 446 at positions which surround the fluidpassageways 544 and 546. The hoses 450 and 452 connect to the fittings458.

Pressurized gas is supplied through the hoses 450 and 452 and into thefluid passageways 544 and 546, respectively, to move the piston 444longitudinally within the cylinder 445. Pressurized gas in the fluidpassageway 544 enters the portion of the cylinder 445 between the piston444 and the rear cylinder cap 500. The pressurized gas admitted throughthe passageway 544 forces the piston 444 to move longitudinally forwardwithin the cylinder 445. The longitudinal forward movement of the pistonmoves the blade deflecting mechanism 440 forward relative to thestationary pinch and cut blade 76, thereby moving the jaw members 150and 152 toward one another, to establish the closed and partially closedpositions of the jaw members (FIGS. 22 and 23). Applying pressurized gasat a relatively higher pressure through the fluid passageway 544 createsa relatively greater forward force on the piston 444, resulting ingreater deflecting force on the jaw members, which results in severingthe leader 64 from the remaining portion of the twist pin 34 (FIG. 10G)as a result of the cutting wedges 154 and 156 moving into contact withone another as the jaw members 150 and 152 move to the fully closedposition (FIG. 23). Applying pressurized gas at a relatively lowerpressure through the fluid passageway 544 creates relatively lesserforward force on the piston 444, resulting in lesser deflecting force onthe jaw members, which results in gripping the leader 64 (FIGS. 10C and22) as a result of the cutting wedges 154 and 156 moving toward but notinto contact with one another in the partially closed position.

Pressurized gas supplied through the fluid passageway 546 enters theportion of the cylinder 445 between the piston 444 and the frontcylinder cap 498. The pressurized gas admitted through the passageway546 forces the piston 444 to move longitudinally rearwardly within thecylinder 445. The longitudinal rearward movement of the piston 444causes the blade deflecting mechanism 440 to move rearward relative tothe stationary pinch and cut blade 76, thereby allowing the jaw members150 and 152 to move away from one another and establish the openposition of the jaw members (FIG. 21).

Longitudinal Movement Subassembly

The principal function of the longitudinal movement subassembly 80 is tomove the grip and cut subassembly 74 longitudinally along the axis 145in the machine 30. Doing so pulls the gripped twist pin 34 into thefinal desired position (FIG. 10E). Thereafter, the grip and cutsubassembly 74 is returned to a position where the pinch and cut blade76 severs the leader 64 (FIG. 10G) at the cutoff end 88 leaving theremaining bulged portion of the twist pin 34 in place and connected tothe vias 60 in the circuit boards 32 of the modules 36 (FIGS. 7 and10H). The secondary function of the longitudinal movement subassembly 80is to rotate the grip and cut subassembly 74 relative to the axis 145.Because the shape of the grip and cut subassembly 74 is not uniformaround the axis 145, it is sometimes desirable to turn the grip and cutsubassembly 74 to obtain more clearance when gripping, pulling andcutting the twist pins and extracting the severed leaders. Among otherreasons, rotation of the grip and cut subassembly 74 may be necessarywhen the column 58 of vias 60 is closely adjacent to a circuit component40 (FIG. 17) attached to the lower surface of the lower circuit board32.

The extension, retraction and rotating functions of the longitudinalmovement subassembly 80 are accomplished by the linear/rotational motor82. The linear/rotational motor 82 is a conventional item, availablecommercially from SMAC of Carlsbad, Calif., USA. The grip and cutsubassembly 74 is connected to the end of the shaft 420 of thelinear/rotational motor 82, as shown in FIGS. 16 and 17. The end of theshaft 420 is threaded and then screwed into a threaded receptacle 558formed in the rear cylinder cap 500 coaxial with the axis 145 (FIG. 20).When connected, an interior passageway in the hollow shaft 420 istherefore aligned with the previously described interior passage formedthrough the grip and cut subassembly 74, as shown in FIGS. 19 and 20.

Details of the linear motor are shown in FIGS. 16 and 17. Thelinear/rotational motor 82 is located in a housing 566. The housing 566is connected to the upright piece 424 of the bracket 442. When operated,the linear/rotational motor 82 extends and retracts the shaft 420relative to the housing 566. Extension of the shaft 420 moves the gripand cut subassembly 74 upward toward the lower circuit board 32 of thecircuit module 36. Retraction of the shaft 420 moves the grip and cutsubassembly 74 in an opposite direction. The linear/rotational motor 82also has the capability to rotate the shaft 420 in any extended orretracted position.

Inside the housing 566 of the linear/rotational motor 82, a main body568 is connected to the shaft 420. A moving electromagnetic coil 570 isconnected to the main body 568 and surrounds a linear permanent magnet572. Current conducted through the coil 570 creates a magnetic fieldwithin the coil 570 which interacts with the magnetic force from thepermanent magnet 572. This force is transferred to the main body 568which moves the shaft 420. The force created is directly related to thecurrent conducted by the coil 570. It is in this manner that theelectrical signals applied to the motor 82 cause the shaft 420 to extendand retract.

The extent of movement of the shaft 420 is determined by a linearencoder 574. The linear encoder 574 includes a linear measurement track576 and a sensor 578 connected to the main body 568. The linearmeasurement track 576 has markings or indications formed at precise anddefinite intervals along its length. The markings or indications of thetrack 576 are sensed by the sensor 578, and the signals from the sensor578 indicate the position of the sensor 578 relative to the track 576.The position of the sensor 578 relative to the track 576 establishes theposition of the shaft 420. The position of the shaft 420 is correlatedto the position of the grip and cut subassembly 74, and specifically thelocation of the cutting wedges 154 and 156 of the pinch and cut blade 76(FIGS. 21-23).

Based on the information available from the linear encoder 574, theupward and downward movement of the grip and cut subassembly 74 allowsthe cutting wedges 154 and 156 to be positioned relative to the lowerprinted circuit board 32 of the circuit module 36 (FIG. 17). Locatingthe cutting wedges 154 and 156 at a predetermined position relative tothe lower printed circuit board establishes the desired location of thecutoff end 88 where the leader 64 is severed. Locating the cutoff end 88too close to the lower printed circuit board 32 makes it difficult orimpossible to grip the twist pin above the cutoff end 88 and remove itif it becomes necessary to disassemble the circuit module 36 or toreplace the previously assembled twist pin with a new twist pin. Acutoff distance which is too long from the lower printed circuit board32 consumes additional space and creates unintended electrical problems.

The vertical height or location of the lower printed circuit board 32 ofthe circuit module 36 is established by use of the linear/rotationalmotor 82. This position is established with each circuit module 36 intowhich twist pins are inserted, because there may be slight differencesin the location of the lower circuit board of each circuit module 36,according to the manner in which it is connected to the pallet 146 (FIG.17). Signals supplied to the linear/rotational motor 82 cause it toretract the grip and cut subassembly 74 to a lowermost position, wherethe upper end of the pinch and cut blade 76 will clear the lower printedcircuit board 32 of the module 36 and any electronic circuit components40 connected to the lower printed circuit board. Thereafter, thelinear/rotational motor 82 extends the shaft 420, causing the grip andcut subassembly 74 to move upward. The upward movement starts at arelatively rapid rate but decreases. When the cutting wedges 154 and 156of the pinch and cut blade 76 contact the lower printed circuit board 32of the module 36, the current drawn by the coil 570 increases becauseadditional magnetic force is required in response to the added physicalresistance caused by contacting the pinch and cut blade 76 with thelower printed circuit board of the circuit module. The increase incurrent is correlated to a decrease in the axial movement of the shaft420, and that relationship is then correlated to the position sensed bythe linear encoder 374. This position sensed by the linear encoder 374defines the lower surface of the lower circuit board of the circuitmodule. This height parameter or distance information is thereafter usedin reference to the location of the lower surface of the lower circuitboard of the circuit module, to assure that the grip and cut subassembly74 is moved to the desired position to cut off the leader 64 at thecutoff end 88.

Rotational movement of the shaft 420 is created by a servo motor 106which is an internal part of the linear/rotational motor 82. The servomotor 106 is connected at the lower end of the shaft 420 and to the mainbody 568 of the motor 82. The servo motor 106 rotates the shaft 420relative to the main body 568. The shaft 420 is rotationally connectedwithin the main body 568 by a conventional rotational bearing assembly(not shown) which does not introduce a significant axial or radialmechanical tolerance in the position of the shaft 420 relative to themain body 568 and the axis 145.

A conventional rotational position encoder 582 is also connected to themain body 568. The rotational encoder 582 determines the rotationalposition of the shaft 420 established by the servo motor 106. Theinformation supplied by the rotational encoder 582 is used by thecontrol system 120 (FIGS. 25A and 25B) to energize the servo motor 106and establish the desired rotational position of the grip and cutsubassembly 74 connected to the shaft 420. The rotational position ofthe grip and cut subassembly 74, as sensed by the rotation encoder 582,is used by the control system to avoid circuit components 40 connectedto the lower surface of the lower printed circuit board 32 of thecircuit module 36. In general, changing the rotational position of thegrip and cut subassembly 74 will not be required if no components orother obstructions are present on the lower surface of the lower printedcircuit board during assembly of the twist pins in the circuit module.

Rapid extension, retraction and rotational movement of the grip and cutsubassembly 74 by the linear/rotational motor 82 creates reactiveforces. These reactive forces are resisted by the bracket 422 (FIGS. 16and 17) which is rigidly connected to the granite slab 174. This rigidconnection to the granite slab 174 and the inertia of the granite slabkeep these reactive forces from adversely affecting the position of thecutting wedges 154 and 156 relative to the leader 64.

With the upper end of the shaft 420 connected to the grip and cutsubassembly 74, as shown in FIGS. 16 and 17, the lower end of the rodextension 530 aligns with and fits within the hollow interior of theshaft 420 (FIG. 20). The conduction tube 162 extends substantiallythrough the grip and cut subassembly 74 and through the full length ofthe hollow shaft 420, past the rotational encoder 582 and the servomotor 106, and out of the bottom of the housing 566. As explainedpreviously, the conduction tube 162 extends from the space between thejaw members 150 and 152, through the hole 540 in the clevis 472, throughthe grip and cut subassembly 74, through the interior passageways in theconnection rod 448 and the piston 444 and the extension rod 530 (allshown in FIG. 19). Thus, the conduction tube 162 establishes acontinuous pathway to conduct the severed leaders 64 from the locationwhere the leader 64 is cut off from the remaining bulged portion of thetwist pin 34 in contact with the vias 60 of the column 58 (FIG. 10G) tothe collection chamber 96 of the leader collection subassembly 90.

Leader Collection Subassembly

The leader collection subassembly 90 is shown in FIGS. 3 and 24. Theprincipal function of the leader collection subassembly 90 is to extractand segregate the severed leaders 64 so that they do not interfere withthe operation of the machine 30. The operations of the leader collectionsubassembly 90 are achieved primarily by the venturi device 92, shown inFIG. 24.

The venturi device 92 creates vacuum or negative pressure within theconduction tube 162 to extract and draw the severed leader away from thegrip and cut subassembly 74 and the longitudinal movements subassembly80 and to propel each severed leader into the collection chamber 96. Thesevered leaders accumulate in the collection chamber 96, out of contactand interaction with the other components of the machine 30.Periodically, the severed leaders are removed from the collectionchamber 96 by the machine operator.

As shown in FIG. 24, the venturi device 92 comprises a housing 590connected to the lower end of the conduction tube 162, below thelocation where the conduction tube 162 extends from the housing 566 ofthe linear/rotational motor 92 (FIG. 17). Pressurized gas is deliveredfrom a hose 592 through an input fitting 600 into an annular chamber 594formed in the housing 590. The annular chamber 594 surrounds a centerbore 596 formed in the housing 590. The center bore 596 is concentricand coaxially aligned with the axis 145. The center bore 596 smoothlycontinues the internal passageway from the conduction tube 162 throughthe housing 590. Orifices 598 extend from the annular chamber 594 intothe center bore 596. The orifices extend inwardly toward the center bore596 in the same direction that the severed leaders are propelled throughthe center bore 596. The cross-sectional sizes of the orifices 598 arerelatively small. The reduced cross-sectional sizes of the orifices 598increase the speed of the gas substantially when it exits the orifices598 into the center bore 596.

The increased speed of the gas from the orifices 598 as it enters thecenter bore 596 reduces the pressure within the center bore 596 relativeto ambient pressure. The reduced gas pressure or partial vacuum iscommunicated through the conduction tube 162 to its upper end. Thereduced pressure causes a downward force (as shown) on the leader 64 ofthe twist pin 34 when it is severed (FIG. 10G), and the severed leader64 is pulled through the conduction tube 162 and is delivered from thecenter bore 596 into the collection chamber 96 by the low pressurecreated in the venturi device 92.

The successful extraction of a severed leader is detected by the opticalsensor 112. Detecting the removal of severed leaders is important indetermining the continued proper functionality of the machine 30. Thefailure to detect a severed leader under circumstances where the controlsystem 120 (FIGS. 25A and 25B) expects a leader to be cut and extracted,indicates a problem with the continued functionality of the machine 30.Under such circumstances, the operation of the machine 30 must besuspended until the source of the problem is corrected. Sources of sucha problem would include an incomplete attempt to cut the leader or asevered leader which has become jammed or hung up in the conduction tube162. Detecting the successful extraction of a severed leader istherefore an important condition for the continued operation of themachine 30.

The optical sensor 112, like the other optical sensors 108 (FIG. 13) and110 (FIG. 14), is formed by a plurality of individual light conductingoptical fibers 626 and 628. The optical fibers 626 and 628 form aconventional optic fiber bundle 630. The optical fibers 626 and 628 areformed of conventional light transmissive material with an index ofrefraction which confines the light to pass along the length of thosefibers. The optical fiber 626 is a center fiber in the bundle 630, andthe other optical fibers 628 become exterior fibers which surround thecenter fiber 626. An end 632 of the fiber bundle 630 is inserted andheld in a receptacle 634 which has been formed transversely into thehousing 590 to intersect the center bore 596. The optical fibers 626 and628 are exposed at the end 632, and are therefore capable oftransmitting and receiving light at their exposed ends. Light from alight source (not shown) is transmitted through the center optical fiber626, and that light exits from the center optical fiber 626 at the end632 to illuminate the center bore 596. Light is reflected within thecenter bore 596 and is picked up and transmitted back to an opticaltransducer (746, FIG. 25B) connected to the exterior optical fibers 628.

When the severed leader moves past the end 632 of the fiber bundle 630,the light received by the exterior fibers 628 at the end 632 is changedas a result of the passage of the severed leader. The changedcharacteristics of the light are evaluated by the optical transducerconnected to the fiber 628, to detect the passage of the severed leader.It is in this manner that the control system 120 (FIGS. 25A and 25B)uses the optical sensor 112 to detect the passage of a severed leaderfrom the venturi device 92.

The collection chamber 96 is formed as a canister 640 having an upperremovable lid 642, as shown in FIG. 24. With the lid 642 attached to thecanister 640, the venturi device 92 is located entirely within theinterior of the canister 642. With the venturi device 92 inside thecanister 640, the severed leaders are confined in the collection chamber96. The lid 642 prevents the severed leaders from bouncing out of thecollection chamber.

A slot 644 extends radially from an outside edge to a center location ofthe lid 642. The slot 644 allows the lid 642 to be placed around theconduction tube 162. The optic bundle 630 and the hose 592 also extendthrough the slot 644. The vertical depth of the canister 640 issufficient to permit the venturi device 92 to move vertically upward anddownward along the axis 145 due to the vertical movement of theconduction tube 162 by the longitudinal movement subassembly 80. Theoptic bundle 630 and the hose 592 have sufficient flexibility and enoughspace exists in the slot 644 to avoid inhibiting the upward and downwardmovement of the venturi device 92.

The canister 640 is attached by a conventional mounting bracket (notshown) to the frame 42 of the machine 30. The machine operator detachesthe canister 640 from the lid 642, and removes the canister 640 from themounting bracket to clear the accumulated severed leaders from thecanister. Thereafter, the empty canister 640 is reconnected to themounting bracket and to the lid 640. Sensors, not shown, preventoperation of the machine 30 by the control system when the canister isremoved for emptying.

Control System

The control system 120 of the machine 30 is shown in FIGS. 25A and 25B.The primary function of the control system 120 is to control andestablish the sequence or process flow of operations performed by themachine subassemblies, as described and shown in FIGS. 26A, 26B and 26C.To do so, the control system 120 utilizes a computer controller 660which has a memory 662 that contains programmed instructions foroperating the machine 30. The memory 662 also contains additionalinformation necessary to carry out the operating instructions, such asthe optical recognition program used for locating the fiducials 144,determining the precise position of each column 58 of vias and potentialobstructions and alignment in the columns 58 by the pattern andintensity of light received by the optical camera 116. Other informationin the memory 662 includes the hole drilling map information by which toinitially establish the locations of the columns 58 of vias, parameterinformation which defines the characteristics of the twist pins 34 (suchas length) to be inserted in particular columns 58 of vias and thelocation and orientation of electronic components 40 which may beattached to the upper and lower surfaces of the upper and lower printedcircuit boards 32 of the circuit modules 36.

A keyboard 664 and a screen display 666 (FIG. 1) are connected to thecomputer controller 660. The keyboard 664, which may include a joystick(not shown), allows the machine operator to supply control informationto the computer controller 660, including manual information formanually advancing the position of the cartridge 50 on the XYpositioning device 98 of the twist pin pickup subassembly 44 and theposition of the circuit modules 36 connected to the pallet 146 on the XYpositioning table 70 of the circuit module positioning subassembly 68.If desired, the optical information derived from use of the opticalrecognition program can be presented on the screen display 666, as wellas operating status information regarding the machine 30. At least onestatus annunciator 668 (FIG. 1) is also connected to the computercontroller 660. Signals are supplied to the status annunciator 668 toindicate the operational status of the machine 30. For example, if theoperation of the machine 30 is halted, the annunciator 668 may deliverboth a visual and an aural signal to alert the machine operator. Thestatus annunciator 668 is preferably connected in plain view of themachine operator, such as on one or both of the vertically extendingupright beams of the frame 72 (FIG. 1).

When the computer controller 660 executes the operating instructions, itgenerates control signals 670 and 672 for controlling the X positionstepper motor 102 and the Y position stepper motor 104, respectively, ofthe XY positioning device 98 of the twist pin pickup subassembly 44(FIGS. 1 and 2). The control signals 670 and 672 are applied to motorcontrollers 674 and 676, respectively, and the motor controllers 674 and676 electrically control the X and Y position stepper motors 102 and 104in accordance with the control signals 670 and 672, to establish thelocation of the pickup head 46 relative to the receptacles 240 of thecartridge 50 (FIG. 2).

The computer controller 660 also supplies a control signal 678 to amotor controller 680 which controls the movement of the linear motor 72connected to the insertion head 56 of the twist pin insertionsubassembly 54 (FIG. 15). The extent of movement of the insertion head56 is determined by the linear position encoder 372 associated with themotor 72 (FIG. 15). Signals 682 from the encoder 372 are supplied to thecomputer controller 660, where the signals 682 are used to establish andverify the position of the twist pin insertion subassembly 54. Thesignals 682 are also used to establish the location of the upper surfaceof the upper circuit board of the circuit module, from which to obtainthe necessary information to determine the position of the insertionnozzle 57 relative to the upper circuit board.

Signals 684 and 686 are supplied by the computer controller 660 tocontrol the motors 100 and 101 of the circuit module positioning table70 of the circuit module positioning subassembly 68. The control signals684 and 686 are supplied to motor controllers 688 and 690, respectively,and the motor controllers 688 and 690 supply energizing signals to themotors 100 and 101 which control the position of the intermediate tablestructure 394 and the upper movement table 390 (FIG. 3) in accordancewith the control signals 684 and 686. The motors 100 and 101 utilizeposition encoders (not shown) which supply feedback signals to thecomputer controller 660 for use in establishing and verifying the exactpositions of the upper movement table 390 and intermediate tablestructure 394. Alternatively, such feedback may be achieved internallywithin the motors 100 and 101, or within the motor controllers 688 and690.

The computer controller 660 also supplies control signals 692 and 694for controlling the axial and rotational movement, respectively, of thelinear/rotational motor 82 of the longitudinal movement subassembly 80which is connected to the grip and cut subassembly 74. The controlsignal 692 controls the extension and retraction of the shaft 420 of thelinear/rotational motor 82, while the control signal 694 controls therotational position of the shaft 420 (FIG. 16). The signals 692 and 694are respectively applied to motor controllers 696 and 698, and the motorcontrollers 696 and 698 establish the extension and retraction androtation of the shaft of the linear/rotational motor 82 in accordancewith the control signals 692 and 694. The linear position encoder 574(FIG. 16) supplies a signal 700 indicative of the position of theextension or retraction of the shaft of the linear/rotational motor 82.The rotational position encoder 582 (FIG. 16) supplies a signal 702indicative of the rotational position of the shaft of thelinear/rotational motor 82. The signals 700 and 702 are used by thecomputer controller 660, or alternatively by the motor controllers 696and 698, to establish and verify the linear and rotational positions ofthe grip and cut subassembly 74. The signal 700 is also used toestablish the location of the lower surface of the lower circuit boardof the circuit module (FIG. 17), from which to obtain the necessaryinformation to determine the position to cut off the leader 64 andestablish the position of the cutoff end 88 of the twist pin remainingin the circuit module. The signal 702 is used to establish and verifythe rotational position of the grip and cut subassembly 74 to avoidcontact with circuit components 40 that may be attached to the lowerprinted circuit board 32 (FIG. 17).

In addition, the computer controller 660 receives input signals 704 fromthe optical camera 116 of the twist pin insertion subassembly 54. Theinput signals 704 are employed in the optical recognition programexecuted by the computer controller 660 to establish the precisepositions, obstructions and alignments of the columns 58 of vias 60.

The control system 120 also controls the application of the pressurizedgas to the grip and cut subassembly 74, to the pickup head 46 of thetwist pin pickup subassembly 44, and to the venturi device 92 of theleader collection subassembly 90. Pressurized gas or air from a source706 is supplied through a filter 730 to a controllable pressureregulator 739. The pressure of the gas from the source 706 is regulatedto a level established by the controllable regulator 739 in adistribution manifold 708 connected to the regulator 739. Controllablepressure regulators 736 and 738 are connected to the distributionmanifold 708. The controllable pressure regulators 736 and 738 regulateand adjust the pressure of the gas delivered from those regulators 736and 738. The pressure of the gas delivered from the regulators 739, 736and 738 is established in accordance with control signals 731, 733 and735 supplied by the computer controller 660. The control signals 731,733 and 735 establish the pressure of the gas delivered from thoseregulators 736, 738 and 739, respectively. Alternatively, thecontrollable regulator 739 may be manually adjustable, in which case itdoes not utilize or respond to the control signal 735.

Gas flow at the pressure established by the controllable regulators 738and 736 is conducted to electrically controlled pneumatic solenoidvalves 710 and 712, respectively. Gas flow at the pressure establishedby the controllable regulator 739 in the manifold 708 is delivered toelectrically controlled pneumatic solenoid valves 714, 716 and 718. Theelectrically controlled pneumatic solenoid valves 710, 712, 714, 716 and718 assume and change flow rates in response to solenoid control signals720, 722, 724, 726 and 728 from the computer controller 660. The controlsignals 720, 722, 724, 726 and 728 cause the solenoids 710, 712, 714,716 and 718 to conduct the pressurized gas through the hoses 450, 452,285 and 592. The control signals 720, 722, 724, 726, 728, 731 and 733(and 735, if the regulator 739 responds to a control signal) aresupplied by the computer controller 660 in response to executing thesystem operating instructions (FIG. 25A).

The pressure regulator 738 reduces the gas pressure from the manifold708 to a level suitable for causing sufficient force on the piston 444to move the blade actuator 442 (FIG. 20) to cause the pinch and cutblade 76 to pinch the leader 64 (FIGS. 10C and 22). The solenoid valve710 connected to the pressure regulator 738 is therefore designated as agrip solenoid valve. The pressure regulator 736 reduces the gas pressurefrom the manifold 708 to a level which is greater than the pressure fromthe regulator 738 but less than the pressure in the manifold 708. Thepressure from the regulator 736 is sufficient to force the pinch and cutblade 76 to cut the leader 64 (FIGS. 10G and 23). The solenoid valve 712connected to the pressure regulator 736 is therefore designated as a cutsolenoid valve. The pressure in the manifold 708 is conducted by thesolenoid valve 714 to the grip and cut subassembly 74 to move the pinchand cut blade 76 to the open position (FIG. 21). The pressure in themanifold 708 is also conducted by the solenoid valve 716 to the pickuphead 46 for removing the twist pins from the receptacles in thecartridge 50 (FIG. 13). In addition, the pressure in the manifold 708 isconducted by the solenoid valve 718 to the venturi device 92 forextracting severed leaders into the collection chamber 96 (FIG. 24). Thesolenoid valves 714, 716 and 718 connected to the manifold 708 aredesignated as an open solenoid valve, a pickup solenoid valve and aventuri solenoid valve, respectively.

The grip and cut solenoid valves 710 and 712 control the flow ofpressurized gas through the hose 450 to the blade activator 442. Theopen solenoid valve 714 controls the flow of pressurized gas through thehose 452 to the blade activator 442. The pickup and venturi solenoidvalves 716 and 718 control the flow of pressurized gas through the hoses285 and 592 to the pickup head 46 and the venturi device 92. Theassertion of the control signals 720, 722, 724, 726 and 728 to thepneumatic solenoid valves 710, 712, 714, 716 and 718 cause thosesolenoid valves to conduct the gas flow. The de-assertion of the controlsignals 720, 722, 724, 726 and 728 cause the pneumatic solenoid valves710, 712, 714, 716 and 718 to cease conducting the gas flow. Turning onand turning off the grip, cut and open solenoid valves 710, 712 and 714control the movement of the piston 444 within the cylinder 445 of theblade activator 442 (FIGS. 18-23) to create the open, partially closedand closed positions of the pinch and cut blade 76 (FIGS. 21-23,respectively). Turning on and off the pickup and venturi solenoid valves716 and 718 control the application of low and high pressure in thepickup head 46 and the venturi device 92.

The solenoid valves 710-718 each have two pneumatic input ports and asingle pneumatic output port. The two input ports are shown in FIG. 25Bon the left-hand side of the solenoid valves 710-718, and the singleoutput port is shown in FIG. 25B on the right-hand side of the solenoidvalves 710-718. The upper ones of the two input ports of the solenoidvalves 710 and 712 (as shown) are directly connected to the regulators738 and 736, respectively, to receive gas flow at the pressureestablished by those regulators. The upper ones of the two input portsof the solenoid valves 714, 716 and 718 (as shown) are directlyconnected to the manifold 708 to receive gas flow at the pressureestablished by the regulator 739. The lower ones of the two input portsof the solenoid valves 710-718 (as shown) are directly connected toambient pressure.

Connected in the manner described in the preceding paragraph, turning onthe solenoid valve 710 causes it to conduct gas flow at the pressureestablished by the regulator 738. The gas flow from the solenoid valve10 is applied to one input port of a check valve 740. Turning off thesolenoid valve 710 causes it to conduct atmospheric pressure to theinput port of the check valve 740. Turning on the solenoid valve 712causes it to conduct gas flow at the pressure established by theregulator 736 to another input port 70 of the check valve 740. Turningoff the solenoid valve 712 causes it to conduct atmospheric pressure tothe other input port of the check valve 740. Turning on the solenoidvalve 714 causes it to conduct gas flow at the pressure in the manifold708 to the hose 452. Turning off the solenoid valve 714 causes it toconduct atmospheric pressure to the hose 452. Turning on the solenoidvalve 716 causes it to conduct gas flow at the pressure in the manifold708 to the hose 285. Turning off the solenoid valve 716 causes it toconduct atmospheric pressure to the hose 285. Turning on the solenoidvalve 718 causes it to conduct gas flow at the pressure in the manifold708 to the hose 592. Turning off the solenoid valve 718 causes it toconduct atmospheric pressure to the hose 592.

The check valve 740 directs the higher of two different pressuresapplied to its two input ports to its single output port. The lower ofthe two different pressures applied to one input port has no influenceon conducting the higher pressure from the other input port to thesingle output port. The check valve 740 conducts the higher inputpressure and the accompanying gas flow to its output port. Thus, in thecircumstance where the turned on solenoid valve 710 applies the pressurefrom the regulator 738 to one input port and the turned off solenoidvalve 712 applies ambient pressure to the other input port, the checkvalve 740 conducts the pressure from the regulator 738 to the hose 450.In the circumstance where the turned on solenoid valve 712 applies thepressure from the regulator 736 to one input port, and the turned offsolenoid valve 710 applies ambient pressure to the other input port, thecheck valve 740 conducts the gas flow from the regulator 736 to the hose450.

The pressurized gas from the source 706 is filtered by the filter 730before the gas is delivered to the regulator 739 and conducted into themanifold 708. The filter 730 removes particles that may be present inthe pressurized gas from the source 706. A pressure switch 732 isconnected to sense the pressure of the gas conducted from the filter 730to the regulator 739. If the pressure drops below a predeterminedminimum threshold, the pressure switch 732 sends a control signal 734 tothe computer controller 660 (FIG. 25A) and the controller ceasesoperation of the machine 30. The operation of the machine 30 ceasesuntil adequate pressure is re-established, as determined by the signal734.

To execute the assembly cycles for the circuit module, the computercontroller 660 delivers the control signals 731, 733 and 735 to theregulators 738, 736 and 739, to establish the appropriate level ofpressure for assembling the twist pins into the via columns. Thecomputer controller 660 also delivers the solenoid control signals 720,722 and 724 to the grip, cut and open solenoid valves 710, 712 and 714.The control signal 720 turns on the grip solenoid valve 710 to conductthe gas flow at the pressure from the regulator 738 to one input port ofthe check valve 740. The control signal 722 turns off the cut solenoidvalve 712 and causes it to supply ambient pressure to the other inputport of the check valve 740. The control signal 724 turns off the opensolenoid valve 714 and causes it to supply ambient pressure through thehose 452. Under these conditions, the pressure from the regulator 738 issupplied through the hose 450 into the portion of the cylinder 445 belowthe piston 444, and ambient pressure is supplied through the hose 452into the portion of the cylinder 445 above the piston 444 (FIG. 20). Thehigher pressure from the hose 450 and the lower ambient pressure fromthe hose 452 establish a pressure differential across the piston 444which moves the piston partially forward in the cylinder 445. Theconnection rod 448, which is connected to the piston 444, moves theblade deflecting mechanism 440 forward with only enough force to deflectthe jaw members 150 and 152 so that the cutting wedges 154 and 156 pinchand grip the leader 64 of the twist pin 34 without severing it (FIG.22). The output pressure from the regulator 738 is adjustable to controlthe extent to which the cutting wedges 154 and 156 pinch into the leader64 without severing it. Adjusting the amount of the relatively lowerpressure gas in this manner is useful to accommodate twist pins havingdifferent thicknesses.

To cut the leader 64, the computer controller 660 delivers the solenoidcontrol signals 720, 722 and 724 to the grip, cut and open solenoidvalves 710, 712 and 714. The control signal 722 turns on the cutsolenoid valve 712 to conduct the gas at the pressure established by theregulator 736 to one input port of the check valve 740. The controlsignal 720 turns off the grip solenoid valve 710 and causes it to applyambient pressure to the other input port of the check valve 740. Therelatively higher pressure gas conducted through the cut solenoid valve712 is conducted by the check valve 740 through the hose 450. Thecontrol signal 724 turns off the open solenoid valve 714 and causes itto conduct ambient pressure gas through the hose 452. The relativelyhigher pressure gas from the hose 450 and the ambient pressure from thehose 452 create a relatively greater pressure differential across thepiston 444 in the cylinder 445, compared to the pressure differentialacross the piston 444 when gripping the leader 64. The relativelygreater pressure differential moves the piston 444 forward in thecylinder 445 with enough force to deflect the jaw members 150 and 152 sothat the cutting wedges 154 and 156 sever the leader 64 from theremaining portion of the twist pin 34 (FIG. 23). The output pressurefrom the regulator 736 is adjustable to obtain sufficient force on thecutting wedges 154 and 156 to sever the leader 64. Adjusting the amountof the relatively higher pressure gas in this manner is useful toaccommodate twist pins having different thicknesses.

To retract the grip and cut subassembly 74, the computer controller 660delivers the solenoid control signals 720, 722 and 724 to the grip, cutand open solenoid valves 710, 712 and 714. The control signal 724 turnson the open solenoid valve 714 to conduct the gas at the pressureestablished by the regulator 739 to the hose 452. The control signals720 and 722 turn off the grip and cut solenoid valves 710 and 712 andcause them to apply ambient pressure to the input ports of the checkvalve 740. Ambient pressure is conducted through the check valve 742 andinto the hose 450. The relatively higher pressure gas from the hose 452and the ambient pressure from the hose 450 create a pressuredifferential across the piston 444 in the cylinder 445, which moves thepiston 444 downward in the cylinder 445 and allows the jaw members 150and 152 to move apart and separate the cutting wedges 154 and 156 to theopen position (FIG. 21). The output pressure from the regulator 736 isadjustable to open the pinch and cut blade 76 quickly enough to avoiddelaying the execution of an assembly cycle, although the more criticalfactor is usually obtaining gas flow from the regulator 739 at asufficient pressure to remove the twist pins from the receptacles in thecartridge and to extract the severed leader.

To remove a twist pin from a receptacle in the cartridge, the computercontroller 660 applies the control signal 726 to the pickup solenoid716. The flow of high-pressure gas through the hose 285 into the venturichamber 280 of the pickup head 46 causes the low pressure or partialvacuum to remove a twist pin from a receptacle 240 in the cartridge 50(FIG. 13). The flow of high-pressure gas to the pickup head 46 alsoconducts the extracted twist pin through the delivery tube 52 to theinsertion head 56, as discussed in connection with FIG. 14. Pulsing thecontrol signal 726 to the pickup solenoid 716 creates the pulses ofpressurized gas in the delivery tube 52 which may be used to attempt tomove a twist pin lodged in the delivery tube 52 or to reseat a twist pinwhich has not been inserted and seated properly, as described above.

To extract a severed leader, the computer controller applies the controlsignal 728 to the venturi solenoid 718. The flow of high-pressure gasthrough the hose 592 to the venturi device 92 causes a low pressure toextract the severed leader 64 and convey it through the conduction tube162 within the grip and cut subassembly 74 and the linear/rotationalmotor 82.

The control system 120 also responds to signals from the optical sensors108, 110 and 112 to monitor the movement of the twist pins 34 and thesevered leaders 64 within the machine 30. The movement of the twist pinsand the severed leaders, and the position of the inserted twist pins isdetermined by light conducted in the exterior optic fibers 292, 332 and628 (FIGS. 13, 14 and 24) of the optical sensors 108, 110 and 112,respectively. The reflected light conducted through the exterior opticfibers from the optical sensors 108, 110 and 112 is conducted to opticaltransducers 742, 744 and 746. The optical transducers 742, 744 and 746convert the received light intensity and pattern into electrical signals750, 752 and 754, and the electrical signals 750, 752 and 754 aresupplied to the computer controller 660. The computer controller 660executes the optical recognition program based on the signals 750, 752and 754 to determine the information relating to the passage andmovement of the twist pins and severed leaders, and the proper seatedposition of the inserted twist pin, and any obstructions in the column58 of vias and the alignment of the vias in the columns, as describedabove.

As shown in FIG. 25A, the computer controller 660 also receives signals758 from the light curtain receivers 118 a, 118 b and 118 c of the lightcurtain 117 (FIG. 1). Should any of the beams extending from the lightcurtain emitters 119 a, 119 b and 119 c to the light curtain receivers118 a, 118 b and 118 c be broken in the manner discussed above, thebroken beam(s) of light will result in the assertion of the controlsignal 758. The computer controller 660 will recognize the assertion ofthe control signal 758, and will immediately cease operation of themachine 30. When all of the light beams between the light emitters andthe light receivers are established and not interrupted, the controlsignal 758 will be de-asserted, and the computer controller 660 willcontrol the machine 30 to execute its automated operations.Alternatively, the signal 758 could represent the signals from all ofthe light curtain receivers 118 a, 118 b and 118 c, and the computercontroller 660 could execute a program to determine when any one of thelight beams between the light curtain receivers 118 a, 118 b and 118 cto the light curtain emitters 119 a, 119 b and 119 c is broken.

Operation Flow Sequence

The functionality of the computer controller 660 in causing the machine30 to execute the automated operations of removing, inserting, gripping,pulling and cutting the twist pin 34 and extracting the severed leader64 while assembling the circuit module 66 our illustrated in FIGS. 26A,26B and 26C. The operations are preferably executed in a flow sequence800. The sequence 800 is described in conjunction with the controlsystem 120 shown in FIGS. 25A and 25B, and the other aspects of themachine shown in FIGS. 1-25. Each of the operations of the sequence 800is identified by a reference number for convenience of description.

The process flow 800 starts at 802 and progresses to 804. At 804, the XYpositioning device 98 of the twist pin pickup subassembly 44, the XYpositioning table 70 of the circuit module positioning subassembly 68,the insertion head 56 of the twist pin insertion subassembly 54, thegrip and cut subassembly 74, and the longitudinal movement subassembly80, are moved to an initialized position. These initialized positionsallow all of the movements required to execute all of the assemblycycles for one circuit module. In addition, the solenoid valves 710-718are operated to move the pinch and cut blade 76 to the open position,and to eliminate any supply of pressurized gas to the pickup head 46 ofthe twist pin pickup subassembly 44 and to the venturi device 92 of theleader collection subassembly 90. Further, all the optical sensors 108,110 and 112 evaluate whether a twist pin, a severed leader or some othertype of obstruction is sensed at this time. No such twist pin, severedleader or the obstruction should be sensed. The functionality of thecamera 116, the light curtain 117 and the pressure of the gas from thesource 706 are also confirmed.

A determination is then made at 806 whether both the circuit module 36and the cartridge 50 have been loaded onto the XY positioning table 70of the circuit module positioning subassembly 68 and XY positioningdevice 98 of the twist pin pickup subassembly 44. Optical sensors, suchas the camera 116, and others (not shown) associated with the XYpositioning device 98 supply a signal to the control system 120 whichindicates that the circuit module 36 and the cartridge 50 have beenloaded. The control system 120 will alert the machine operator from theannunciator 668 if one or both of the circuit module 36 or the cartridge50 have not been loaded.

If the determination at 806 is negative, then the process flow 800 loopsback to 806 and the determination is repeated until the circuit module36 and the cartridge 50 have been loaded. When the determination at 806is affirmative, the process flow 800 continues to 808.

At 808, the operational information and parameters that are specific toassembling the circuit module 36, the printed circuit board holedrilling map information, the information describing the locations ofthe receptacles 240 in the cartridge 50 and the type and characteristicsof the twist pins located in each of the receptacles 240, informationdescribing the location and orientation of any circuit components 40attached to the upper and lower printed circuit boards 32 of the circuitmodule 36, the optical recognition program, the light curtain operatingprogram, electric motor operating and control programs, and the otherinformation necessary to control the machine 30 in the manner previouslydescribed, is then loaded or accessed in the memory 662 for use by thecomputer controller 660. Some of this information may be supplied by themachine operator through the keyboard 664.

Next, the location of the fiducials 144 of the circuit module 36 withinthe XY coordinate system of the XY positioning table 70 are identified,at 810. The fiducials 144 are located by the machine operator manuallymoving the XY positioning table 70 with input commands from the keyboard664 or a joystick, and viewing the position and images on the screen 666viewed by the camera 116. By manual movement in this manner, thefiducials 144 are precisely located. The machine operator registers theexact location of the fiducials 144 by input signals that the keyboard664, and the exact location of those fiducials is established by thecomputer controller 660 based on the positions of the motors 100 and 101of the XY positioning table 70 at that time. Locating three fiducials144 in this manner establishes the complete orientation by which thehole drilling map information is then correlated to the locations of thevias 60 in the upper circuit board 32 of the circuit module 36.

An ordered list of XY coordinates or positions of the XY positioningdevice 98 corresponding to the locations of the receptacles 240 in thecartridge 50 is then established at 812. The ordered list of receptaclecoordinates may be contained within or established from the informationand parameters loaded at 808.

At 814, the precise vertical height or location of the upper circuitboard 32 of the circuit module 36 is identified. The location of theupper circuit board 32 is measured on the Z-axis coordinate with theinsertion head 56 and the insertion nozzle 57. The height of the uppercircuit board 32 is established by moving the insertion head 56 towardthe upper circuit board until the insertion nozzle 57 physicallycontacts the top circuit board, as described above. The contact positionis determined by the linear encoder 372, and that position is thereafteremployed to establish the optimal distance between the insertion nozzle57 and the upper circuit board for inserting the twist pins, asdescribed previously.

It is desirable to establish the height of the upper printed circuitboard in at least three different desired contact points, to determinewhether the upper surface of the upper circuit board deviates from aplane parallel to the plane defined by the XY positioning table 70.Information regarding the amount of planar deviation of the uppercircuit board is derived from the three measurement points and isthereafter used to interpolate the actual precise height or location ofthe upper surface of the upper circuit board at the location of each via60, or to alert the operator that the circuit module 36 should be resetin the pallet 146 to achieve the desired coplanar orientation.

At 816, the distance to the lower circuit board 32 of the circuit module36 is established. The linear/rotational motor 82 of the longitudinalmovement subassembly 80 moves the grip and cut subassembly 74 upwarduntil the pinch and cut blade 76 physically contacts the lower circuitboard 32. The determined position of the lower printed circuit board isestablished as described above and is used to establish the desiredheight of the cutoff end 88 and when pulling the leader 64.

Any deviation in the plane of the lower circuit board from the plane ofthe upper movement table 390 of the XY positioning table 70 is alsodetermined in a manner similar to that described above at 814. Anydeviation in the co-planar relationship of the lower printed circuitboard is thereafter used to interpolate the height of the lower surfaceof the printed circuit board, or if the deviation is significant, toalert the machine operator of the necessity to reset the circuit module36 in the pallet 146 or to utilize another circuit module because anassembly problem may have skewed a generally planar relationship betweenthe upper and lower circuit boards of that module.

It is desirable to establish the height of the lower printed circuitboard in at least three different desired contact points, to determinewhether the upper surface of the lower circuit board deviates from aplane parallel to the plane defined by the XY positioning table 70.Information regarding the amount of planar deviation of the lowercircuit board is derived from the three measurement points and isthereafter used to interpolate the actual precise height or location ofthe lower surface of the upper circuit board at the location of each via60, or to alert the operator that the circuit module 36 should be resetin the pallet 146 to achieve the desired coplanar orientation.

An ordered list of the XY positions or coordinates of the columns 58 ofvias is then established at 818. The ordered list is established fromthe hole drilling map information loaded at 808, based on the locationsof the fiducials which are located at 810.

The operations 820-828 of the process flow 800 establish and verify theprecise location of each via column 58, as well as determine that eachvia column 58 is not obstructed and not sufficiently misaligned toimpede the successful assembly of a twist pin in that column.Establishing the precise location of each column 58 of vias allows thevia column 58 to be positioned directly beneath the insertion nozzle 57coaxially with the axis 145. Any obstruction and misalignment of the viacolumn 58 could impede the proper insertion and seating of the twistpin, as discussed above.

Under conditions where an obstruction or misalignment is recognized, thecoordinates of the via column 58 are added to a skip list, at 826. Theskip list designates those via columns 58 into which twist pins will notbe inserted automatically by the machine 30. The skip list is providedto the machine operator who may manually inspect each via column 58 ofthe skip list before any twist pins are inserted in the other viacolumns by the machine 30. The machine operator may inspect the viacolumns of the skip list and then decide to manually remove some of thevia columns from the skip list. Alternatively, the machine operator mayelect to have the machine 30 insert twist pins in all of the via columnsthat are not on the skip list and then determine whether twist pins canbe manually assembled in the via columns on the skip list by humanaction. The operations 820-828 may be executed for less than all of thevia columns 58 or not executed altogether depending on the accuracy ofthe circuit board manufacturing process.

At 820, the first via 58 within the ordered list of via columns 58 ispositioned under optical axis 344 of the optical camera 116, using thehole drilling map information. At 822 the precise location of the viacolumn is determined using the optical recognition software. If the viacolumn 58 is precisely centered at the optical axis 344 of the opticalcamera 116, the optical recognition software will determine that centerof the upper via 60 in the column 58 is at the location specified by thehole drilling map information. If the upper via 60 in the column 58 isnot precisely centered, the optical recognition software will analyzethe light intensity and pattern, and then move the XY positioning table70 until the light intensity and pattern indicates that the upper via 60in the column 58 is centered with respect to the optical axis 344. Thisidentified offset or deviation from the hole drilling map information isused to modify the hole drilling map information to later locate theupper via 60 of the column 58 coincident with the axis 145 of theinsertion nozzle 57, when a twist pin is inserted. In this manner, anyoffset detected at 822 is used to update the coordinates for the viacolumn 58 to establish the precise location of the center of the uppervia 60 of the column 58.

At 824 a determination is made as to whether the column 58 of vias 60 isobstructed or misaligned. The via column 58 which is evaluated at 824 isthe same via column from which the center location of the upper via 60was determined at 822. If the via column 58 is obstructed, partiallyobstructed or misaligned, the light intensity and image patternrecognized by the camera 116 will recognize the situation and thecoordinates of that via column 58 will be added to the skip list at 826.

If the determination at 824 is negative, or after the via column hasbeen added to the skip list at 826, a determination is made at 828 ofwhether all of the via columns 58 of the circuit module have beenchecked for location and obstruction and misalignment. If thedetermination at 826 is negative, then the next via column 58 of thecircuit module in the ordered list of via columns is positionedunderneath the optical axis 334, as shown at 830. The process flowreturns to 822 where the operations 824, 826 and 828 are repeated. Thelooping from 828 to 830 to 822 continues until all of the via columns 58of the circuit module have been evaluated for position, obstructions andmisalignment. A complete evaluation results in an affirmativedetermination at 828, and then the process flow 800 continues to 832.

At 832, the process flow 800 commences operations to assemble a singletwist pin 34 into one column 58 of vias 60 in a single assembly cycle.The operations commencing at 832 are made possible as a result ofperforming the operations 804-830.

At 832, certain counter variables associated with each assembly cycleare reset to zero. The counter values reset to zero at 830 establish thenumber of repeated operations permitted to successfully assemble eachtwist pin in each via column 58. The counter values reset at 832determine the number of pin removal errors, pin seated errors, pin retryerrors and pin cut errors permitted during an assembly cycle. Thecounter values reset at 832 may or may not be different from oneanother.

At 834, the XY positioning device 98 moves the cartridge 50 to align thenext receptacle 240 in the ordered list of receptacles established at812 with the pickup head 46. If the execution of the operation at 834 isthe first execution, the first receptacle 240 in the ordered list ofreceptacles is aligned with the pickup head 46 at 834.

Next at 836, the XY positioning table 70 moves the pallet 146 and theattached circuit module to make the center location of the first viacolumn 58 within the ordered list of column coordinates established at818 coincident with the axis 145 of the insertion nozzle 57. If theexecution of the operation at 836 is the first execution, the next viacolumn 58 is aligned with the axis 145 of the insertion nozzle 57, at836.

The pickup solenoid 716 is energized at 838 to remove the twist pin fromthe receptacle 240 whose position was established at 834. The energizedpickup solenoid 716 flows pressurized gas to the pickup head 46, and theresulting low pressure gas removes the twist pin from the receptacle 240and delivers it into the delivery tube 52. The pressurized gas carriesthe twist pin through the delivery tube to the insertion nozzle 57,where the precise positioning of the via column 58 coincident with theaxis 145 of the insertion nozzle 57 ensures that the leader 64 of thetwist pin will enter the column 58 of vias 60 as intended.

At 840, a determination is made whether the twist pin was successfullyremoved from the receptacle 240 and the cartridge 50. A successfulremoval of the twist pin will cause it to pass through the passageway272 of the pickup head 46. The optical sensor 108 optically determinesthe removal of the twist pin from the cartridge 50 and the passage ofthe twist pin through the pickup head 46. A successful removal of thetwist pin results in an affirmative determination at 840.

If the light from the optical sensor 108 is not of the predeterminedexpected duration and intensity indicative of a successful pin removal,the determination at 840 is negative, indicating that the twist pin wasnot successfully removed from the cartridge 50. Under suchcircumstances, it is assumed that a twist pin was not present in thereceptacle aligned with the pickup head at 834, or that the twist pin inthe receptacle aligned with the pickup head at 834 is stuck in thereceptacle and cannot be removed. Under such circumstances, the processflow 800 undertakes the operations 842-848 to access another receptacleand attempt to remove the twist pin from that other receptacle forinsertion. Before doing so, the supply of pressurized gas delivered tothe pickup head 46 is terminated, because the previous twist pin removalattempt was not successful.

At 842, the pin removal error count is incremented. At 832, the pinremoval error count was set to zero at the commencement of the assemblycycle. Incrementing the pin removal error count therefore represents oneattempt to remove a twist pin from the cartridge 50. At 844, adetermination is made whether the pin removal error count is equal to apredetermined value. The predetermined value involved at 844 is apredetermined number of permitted retry attempts to remove the twist pinfrom the cartridge 50. A negative determination at 844 indicates thatthe predetermined number of retries has not been reached, and permitsthe XY positioning device 98 to move the cartridge 50 into a positionwhere the next receptacle 240 in the ordered list of receptacles isplaced in alignment with the pickup head 46, at 846. Thereafter anotherattempt to remove the twist pin at 838 occurs, followed by adetermination at 840 of whether the pin was successfully removed. Arepetition of the operations at 842, 844 and 846, which is initiated bythe negative determination at 840, continues until the allowed number ofretries is exceeded, as determined by an affirmative determination at844. Under that circumstance, the pin removal error count is reset tozero at 848 to establish the permitted number of repeated attempts tosuccessfully remove the next twist pin in the next assembly cycle. Themachine operator is notified at 850 that manual intervention is requiredbecause continuing the automated assembly cycle is no longer possible oradvisable. Automated operation of the machine 30 is halted.

The machine operator is notified by visual and aural signals from theannunciator 668. Details concerning the error or type of problem arepresented to the machine operator on the display screen 666. After themachine operator determines and corrects the condition which led to thepin removal error count reaching the predetermined maximum number ofretries, the machine operator signals the computer controller 660 withthe keyboard 664 to continue execution of the process flow 800.

An affirmative determination at 840 indicates that the twist pin hasbeen removed successfully from the cartridge 50 and the process flow 800continues to 852. At 852, a determination is made whether the twist pinwas successfully received by insertion nozzle 57. The optical sensor 110supplies signals which identify the successful passage of a twist pinthrough the insertion nozzle 57. Successful receipt of the twist pin bythe insertion nozzle 57 results in an affirmative determination at 852.A negative determination at 852 indicates that the twist pin was notreceived. Under such circumstances, after the twist pin was successfullyremoved from the cartridge 50 as determined at 840, there is a highlikelihood that the twist pin is stuck in the delivery tube 52. Theoperations at 854, 856 and 858 are thereafter performed in an attempt todislodge the twist pin from the delivery tube 52.

A negative determination at 852 causes the pin received error count tobe incremented at 854. The pin received error count was originally setto zero at 832 to establish the maximum number of permitted retryattempts to receive a twist pin at the insertion nozzle 57. At 856, adetermination is made whether the pin received error count is equal to apredetermined value. The predetermined value is the maximum number ofpermitted attempts to retry delivering the twist pin to the insertionnozzle 57. So long as the maximum number of permitted attempts to retrydelivering the twist pin from the delivery tube does not equal thepredetermined value, as established by a negative determination at 856,each retry attempt involves creating a single pulse or blast of gasdelivered through the delivery tube 52 by applying a pulse controlsignal 726 to the pickup solenoid 716 at 858. Pulsing the pickupsolenoid 716 has the effect of briefly turning on and then turning offthe pressurized gas delivered to the pickup head 46. The pulse of gasflows through the delivery tube 52 and may dislodge or otherwise forcethe twist pin into the insertion nozzle 57.

After the pulse of pressurized gas is delivered at 858, a loop back to852 occurs where a determination is made of whether the twist pin hasbeen received in the insertion nozzle 57. A negative determination at852 results in again executing the operations 854, 856 and 858. Arepetition of these operations is executed until the pin received errorequals the predetermined value, as established by an affirmativedetermination at 856. Thereafter, the pin received retry count is resetat 860 to establish the permitted number of repeated attempts tosuccessfully deliver the twist pin in each via column 58 during the nextassembly cycle. The machine operator is notified of the condition at850. Operation of the machine 30 is halted.

Details concerning the error or type of problem are presented on thedisplay screen 666. After the machine operator determines and correctsthe condition which led to the pin received error count reaching thepredetermined maximum number of retries, the machine operator signalsthe computer controller 660 to continue execution of the process flow800, by use of the keyboard 664.

An affirmative determination at 852 indicates that the twist pin wasreceived by the insertion nozzle 57. At 862, it is determined whetherthe twist pin is properly seated in the via column 58 of the circuitmodule 36. The twist pin 34 may have traveled past the optical sensor110 enough for the determination at 852 to be affirmative, and yet notbe properly seated within the via column 58 as expected. Under properseating conditions, the tail end 129 of the twist pin is positionedadjacent to optical sensor 110. The resulting optical signaldistinguishes the properly seated condition from a condition where notwist pin is detected (which would indicate the failure to receive atwist pin), and the condition where the twist pin is present across fromthe optical sensor 110 or at least the tail end 129 of the twist pin ishigher than the anticipated location (which would indicate an improperlyseated condition). Under such circumstances, after the twist pin wassuccessfully received by the insertion nozzle 57, as determined at 852,the operations at 864, 866, 868 are thereafter performed in an attemptto properly seat the twist pin in the via column 58.

When the determination at 862 is negative, indicating an improperlyseated twist pin, the pin seated error count is incremented at 864. Thepin seated error count value is reset to zero at 830 to establish thepermitted number of repeated attempts to successfully seat each twistpin in each via column 58 during the next assembly cycle.

Next at 866, a determination is made whether the pin seated error countis equal to a predetermined value. The predetermined value used at 866indicates a predetermined number of retries permitted to attempt toproperly seat the twist pin. So long as the maximum number of permittedattempts to retry seating the twist pin does not equal the predeterminedvalue, as established by a negative determination at 856, each retryattempt involves creating a single pulse or blast of gas deliveredthrough the delivery tube 52 by applying a pulse control signal 726 tothe pickup solenoid 716 at 868. Pulsing the pickup solenoid 716 has theeffect of briefly turning on and then turning off the pressurized gasdelivered through the pickup head 46. The pulse of gas flows through thedelivery tube 52 and the insertion nozzle 57. The pulse of gas may moveor otherwise force the twist pin into the properly seated position inthe via column 58.

The process flow then reverts to 862 where the signals from the opticalsensor 110 are again evaluated to determine whether the twist pin isproperly seated. The loop formed by 864, 866 and 868 is repeated untilthe twist pin is properly seated (represented by an affirmativedetermination at 862) or the pin seated error count equals thepredetermined value of permitted retries (represented by an affirmativedetermination at 866).

An affirmative determination at 866 institutes a pin clear procedure at872. The pin clear procedure at 872 involves using the grip and cutsubassembly 74 and the longitudinal movement subassembly 80 to attemptto grip the leader 64 and pull the twist pin completely through the viacolumn 58, thereby completely removing the improperly seated twist pin.Of course, if the leading end 78 of the leader 64 of the twist pin doesnot extend sufficiently below the lower surface of the lower circuitboard, it will not be possible to grip and pull the twist pin from thevia column 58. In which case, the pin clear procedure 872 cannot beexecuted.

A determination is made at 874 whether the twist pin 34 was successfullyremoved from the via column. Successful removal of the twist pin willcause the optical sensor 112 to detect the twist pin 34 passing throughthe venturi device 92. Of course, when the pin clear procedure at 872 isinitiated, the venturi solenoid 718 is turned on to create low pressurefor extracting the twist pin through the conduction tube 162. The pinclear procedure 872 may involve repeatedly gripping and pulling thetwist pin, without cutting the twist pin. Such repeated gripping andpulling may have the effect of forcing the twist pin into the conductiontube 162. As a further alternative, pieces of the twist pin can be cutoff from the remaining portion of the twist pin, and the separate piecesare then extracted. In the circumstance of cutting the twist pin intopieces during the pin clear procedure 872, the number of pieces and theposition in which they are cut is recognized by the computer controller660 to determine when the entire twist pin has been removed from the viacolumn 58.

An affirmative determination at 874 indicates that the twist pin hasbeen successfully removed. Then at 876, the next receptacle in theordered list of receptacles is positioned beneath the pickup head 46 aspreviously described at 846 in preparation for another insertion attemptin the current via column 58, and the process flow 800 reverts to 838where a new twist pin is removed, inserted and assembled.

A negative determination at 874 causes the pin seated error count toreset to zero at 877 to establish the permitted number of repeatedattempts to successfully seat the next twist pin in the next assemblycycle. The machine operator is notified at 850 that intervention isrequired. If the operator is thereafter successful in remedying theproblem of the twist pin not being properly seated, and that problem iscleared by the operator, the process flow 800 reverts to 838 where a newtwist pin is removed, inserted and assembled as previously described.

An affirmative determination at 862 indicates that the twist pin isproperly seated. The properly seated condition indicates that the twistpin is ready to be gripped and pulled to the position where the bulges84 contact the sidewalls 86 of each via 60.

The twist pin is gripped and pulled in the manner previously describedat 880. The gripping and pulling at 880 is accomplished by use of thegrip and cut subassembly 74 and the longitudinal movement subassembly 80in the manner previously described. Immediately thereafter at 882, theleader is cut, again using the grip and cut subassembly 74 and thelongitudinal movement subassembly 80 in the manner previously described.Prior to gripping and pulling at 880 and cutting at 882, the venturisolenoid 718 is energized to create a low pressure for extracting thesevered leader.

Next at 884, the optical sensor 112 is used to determine whether theleader was extracted. The determination of whether the leader wasextracted is established by the optical signals indicative of thesevered leader passing through the venturi device 92. The determinationof whether the leader was extracted at 884 also indicates whether theleader was cut, because the leader cannot be extracted unless it was cutoff from the remaining portion of the twist pin. If the leader portion64 is successfully cut from the twist pin 34, the leader 64 will passfrom the venturi device 92 into the collection chamber 96. Thedetermination at 884 is affirmative when the signal generated from theoptical sensor 112 indicates that the leader portion 64 has passedthrough the venturi device 92; otherwise the determination at 884 isnegative.

If the determination at 884 is negative, then the pin cut error count isincremented at 886 and a subsequent determination is made at 888 as towhether the pin cut error count is equal to a predetermined value. Thepredetermined value involved at 888 is a predetermined number ofpermitted retry attempts to cut and extract the leader from theremaining portion of the twist pin. If the determination at 888 isnegative, indicating that an additional attempt to cut and extract theleader from the remaining portion of the twist pin is permitted, anotherattempt to cut the leader portion 64 is made at 882. Thereafter, adetermination is made at 884 as to whether the leader was cut andextracted.

The sequence of operations represented by 882, 884, 886 and 888 isrepeated until the predetermined value is reached at 888. Theaffirmative determination at 888 results in resetting the pin cut errorcount at 889. The pin cut error count is reset to zero to establish thepermitted number of repeated attempts to successfully cut the leader inthe next assembly cycle. The operator is notified at 850. Thereafter, ifthe operator is successful in remedying the problem of the twist pin notbeing cut and the leader successfully extracted, and that problem iscleared by the operator (probably by removing the twist pin which wasnot cut or the leader which was not extracted), the process flow revertsto 838 where a new twist pin is removed, inserted and assembled aspreviously described.

An affirmative determination at 884 indicates that the leader was cutfrom the remaining portion of the twist pin assembled in the via column58 and that the severed leader was extracted from the conduction tube162 and delivered into the collection chamber 96. The optical sensor 112provides signals which are evaluated to make the affirmativedetermination at 884.

An affirmative determination at 890 indicates that the twist pin hasbeen successfully assembled in the via column 58 and that one assemblycycle has been completed. Thereafter at 900, the subassemblies 44, 54,68, 74, 80 and 90 are prepared for the next assembly cycle in whichanother twist pin will be successfully inserted into another via column58.

At 902 a determination is made whether all of the via columns 58 in theordered list of columns have been filled with twist pins for the circuitmodule, except for the via columns which are described on the skip list.If the determination at 902 is negative, all of the via columns of thecircuit module have not yet been assembled with twist pins. To continueassembling twist pins in the available via columns of the circuitmodule, the process flow 800 loops back to 832 where the next assemblycycle for the next twist pin is commenced. More twist pins are assembledinto the circuit module in subsequent cycles until all of the availableand intended via columns 58 of the circuit module have been assembledwith twist pins, at which point the determination at 902 is affirmative.The affirmative determination at 902 indicates that the assembly oftwist pins in the circuit module has been completed to the extentpossible by the automated actions of the machine 30, and then theprocess flow 800 ends at 904.

If more than one circuit module 36 is located on the pallet 146, theprocess flow 800 will repeat for the next subsequent circuit module. Therepetition for the next subsequent circuit module may not commence at804, but instead may commence at operation 814, because the operations804-812 may be applicable to all of the multiple circuit modules 36located on the pallet.

As has been described above, the machine 30 automatically executes allof the operations necessary to assemble a twist pin or z-axisinterconnector in columns 58 of vias 60 in the circuit boards 32 of athree-dimensional circuit module 36. The automation provided by thesingle machine 30 avoids the need for separate machines, multiplemachine operators and constant machine operator attention to assemblethe twist pins in the circuit modules. The machine 30 automaticallyachieves significant precision without operator intervention or controlto assemble the twist pins in the circuit modules. The automated natureof the machine 30 allows significant numbers of circuit modules to beassembled relatively quickly, thereby reducing manufacturing expenseswhile enhancing the quality of the assembly. Many other advantages andimprovements will become apparent upon fully appreciating the manyaspects of the present invention.

Presently preferred embodiments of the present invention and many of itsimprovements have been described with a degree of particularity. Thisdescription is a preferred example of implementing the invention, and isnot necessarily intended to limit the scope of the invention. The scopeof the invention is defined by the scope of the following claims.

1. A method of automatically assembling z-axis interconnectors intocolumns of aligned vias in stacked printed circuit boards of a circuitmodule in repetitively executed assembly cycles, each assembly cyclecomprising: using an interconnector having a leader portion and aconnection portion, singulating an interconnector from a plurality ofthe interconnectors; moving the circuit module and an insertion nozzlerelative to one another to align an unoccupied via column with theinsertion nozzle; conveying the singulated interconnector through adelivery tube; delivering the interconnector from the delivery tube intothe insertion nozzle; delivering the interconnector from the insertionnozzle into the aligned via column; seating the interconnector in thealigned via column with the leader portion extending through the viacolumn to a position below a lower circuit board of the circuit module;gripping the leader portion below the lower printed circuit board;pulling the gripped leader portion until the connection portion movesthrough the aligned via column into contact with the vias of the column;severing the leader portion from the connection portion at a cutofflocation adjacent to the lower circuit board; extracting the severedleader portion; and automatically repeating a next assembly cycle aftercompleting a previous assembly cycle until interconnectors have beenassembled into a substantial majority of the via columns of the circuitmodule.
 2. A method as defined in claim 1, further comprising: sensingconveying of the interconnector into the delivery tube; sensingdelivering of the interconnector from the delivery tube into theinsertion nozzle; sensing proper seating of the interconnector in thealigned via column; and ceasing automated execution of the assemblycycle if the interconnector does not pass into the delivery tube or ifthe interconnector does not pass from the delivery tube into theinsertion nozzle or if the interconnector is not properly seated.
 3. Amethod as defined in claim 2, further comprising: gripping and pullingthe gripped leader as aforesaid until the connection portion is pulledcompletely through the aligned via column, upon sensing that theinterconnector is not properly seated in the aligned column.
 4. A methodas defined in claim 1, further comprising: storing the plurality ofinterconnectors in a cartridge having a plurality of receptacles witheach interconnector in a separate receptacle; aligning each receptaclewith a pickup head to remove the interconnector in the receptacle;sensing the passage of the interconnector from the receptacle into thedelivery tube; and aligning another receptacle with the pickup head toremove a different interconnector from the other receptacle upon sensingthat one interconnector was not removed from the receptacle previouslyaligned with the pickup head.
 5. A method as defined in claim 1, furthercomprising: sensing the passage of the severed leader into an extractiontube; sensing the passage of the severed leader from the extraction tubeinto a collection chamber; and ceasing automated execution of theassembly cycle if the severed leader does not pass into the extractiontube or if the interconnector does not pass from the extraction tubeinto the collection chamber.
 6. A method as defined in claim 1, furthercomprising: defining a delivery axis through the insertion nozzle alongwhich the interconnectors are delivered for insertion into the viacolumn; perceiving images along an optical axis parallel to the deliveryaxis of the insertion nozzle; moving the circuit module and theinsertion nozzle relative to one another to align an unoccupied viacolumn with the optical axis; establishing a center position of an uppervia in the upper circuit board of the via column from the perceivedimages; and aligning the upper via in the unoccupied via column with thedelivery axis for insertion of the interconnector by using the opticallyestablished center position.
 7. A method as defined in claim 6, furthercomprising: using hole drilling map information which specifieslocations of the vias created from holes formed during fabrication ofthe printed circuit boards and the optically established center positionto align the delivery axis with the via column.
 8. A method as definedin claim 1, further comprising: defining a delivery axis through theinsertion nozzle along which the interconnectors are delivered forinsertion into the via column; perceiving images along an optical axisparallel to the delivery axis of the insertion nozzle; moving thecircuit module and the insertion nozzle relative to one another to alignan unoccupied via column with the optical axis; identifying anyobstruction to the insertion of the interconnector in the via columnfrom the perceived images; and not executing an assembly cycle on eachvia column in which an obstruction is identified.
 9. A method as definedin claim 1, further comprising: defining a delivery axis through theinsertion nozzle along which the interconnectors are delivered forinsertion into the via column; perceiving images along an optical axisparallel to the delivery axis of the insertion nozzle; moving thecircuit module and the insertion nozzle relative to one another to alignan unoccupied via column with the optical axis; identifying apredetermined amount of misalignment of the vias in the aligned viacolumn from the perceived images; and not executing an assembly cycle oneach via column in which the predetermined amount of misalignment of thevias in the aligned via column is identified.
 10. A method as defined inclaim 1, further comprising: establishing the height of the uppercircuit board in the circuit module by moving the insertion nozzlevertically to contact the upper circuit board of the circuit module. 11.A method as defined in claim 1, further comprising: using componentlocation information which defines the location and orientation ofelectronic components connected to the upper circuit board of thecircuit module; and moving the insertion nozzle vertically toward andaway from the upper circuit board during at least some of the assemblycycles executed to avoid contact with the electronic components whileassembling the interconnectors in the via columns.
 12. A method asdefined in claim 1, further comprising: gripping and cutting the leaderportion with a blade member; and establishing the height of the lowercircuit board in the circuit module by moving the blade membervertically to contact the lower circuit board of the circuit module. 13.A method as defined in claim 12, further comprising: using componentlocation information which defines the location and orientation ofelectronic components connected to the lower circuit board of thecircuit module; rotating the blade member during at least some of theassembly cycles executed to avoid contact with the electronic componentson the lower circuit board while assembling the interconnectors in thevia columns.
 14. A method as defined in claim 1, wherein eachinterconnector is a twist pin.